text:
\textbackslash alpha\$ Cen A (\$5.4\_\{-0.2\}\^\{+1.2\}\$ Gyr), appear remarkably similar, pointing to a convergence of magnetic heating rates for G2 main-sequence stars older than \$\textbackslash approx 2-4\$ Gyr. But the B component's X-ray (0.3-2.5 keV) flux lies 20\$\textbackslash times\$ below a well-known minimum level reported by Schmitt. As reported for \$\textbackslash alpha\$\textasciitilde Cen\textasciitilde A, the coronal temperature probably lies below that detectable in soft X-rays. No solar UV flux spectra of comparable resolution to stellar data exist, but they are badly needed for comparison with stellar data. Center-to-limb (C-L) variations are re-evaluated for lines such as \textbackslash ion\{Ca\}\{2\} through to X-rays, with important consequences for observing activity cycles in such features. We also call into question work that has mixed solar intensity-intensity statistics with flux-flux relations of stars.},
  archivePrefix = {arXiv},
  eprint = {1710.05088},
  eprinttype = {arxiv},
  file = {/Users/Oliver/Zotero/storage/6MI58T69/Judge et al. - 2017 - The magnetic future of the Sun.pdf;/Users/Oliver/Zotero/storage/R4Z6GSTC/1710.html},
  journal = {arXiv:1710.05088 [astro-ph]},
  keywords = {Astrophysics - Solar and Stellar Astrophysics},
  primaryClass = {astro-ph}
}

@article{kallinger+2012,
  title = {Evolutionary Influences on the Structure of Red-Giant Acoustic Oscillation Spectra from 600d of {{Kepler}} Observations},
  author = {Kallinger, T. and Hekker, S. and Mosser, B. and De Ridder, J. and Bedding, T. R. and Elsworth, Y. P. and Gruberbauer, M. and Guenther, D. B. and Stello, D. and Basu, S. and Garc{\'i}a, R. A. and Chaplin, W. J. and Mullally, F. and Still, M. and Thompson, S. E.},
  year = {2012},
  month = may,
  volume = {541},
  pages = {A51},
  doi = {10.1051/0004-6361/201218854},
  abstract = {Context. It was recently discovered that the period spacings of mixed pressure/gravity dipole modes in red giants permit a distinction between the otherwise unknown evolutionary stage of these stars. The Kepler space mission is reaching continuous observing times long enough to also start studying the fine structure of the observed pressure-mode spectra. \\
 Aims: In this paper, we aim to study the signature of stellar evolution on the radial and pressure-dominated l = 2 modes in an ensemble of red giants that show solar-type oscillations. \\
 Methods: We use established methods to automatically identify the mode degree of l = 0 and 2 modes and measure the large ({$\increment\nu$}\textsubscript{c}) and small ({$\delta\nu$}\textsubscript{02}) frequency separation around the central radial mode. We then determine the phase shift {$\smallin$}\textsubscript{c} of the central radial mode, i.e. the linear offset in the asymptotic fit to the acoustic modes. Furthermore we measure the individual frequencies of radial modes and investigate their average curvature. \\
 Results: We find that {$\smallin$}\textsubscript{c} is significantly different for red giants at a given {$\increment\nu$}\textsubscript{c} but which burn only H in a shell (RGB) than those that have already ignited core He burning. Even though not directly probing the stellar core the pair of local seismic observables ({$\increment\nu$}\textsubscript{c}, {$\smallin$}\textsubscript{c}) can be used as an evolutionary stage discriminator that turned out to be as reliable as the period spacing of the mixed dipole modes. We find a tight correlation between {$\smallin$}\textsubscript{c} and {$\increment\nu$}\textsubscript{c} for RGB stars and unlike less evolved stars we find no indication that {$\smallin$}\textsubscript{c} depends on other properties of the star. It appears that the difference in {$\smallin$}\textsubscript{c} between the two populations becomes smaller and eventually indistinguishable if we use an average of several radial orders, instead of a local, i.e. only around the central radial mode, large separation to determine the phase shift. This indicates that the information on the evolutionary stage is encoded locally, more precisely in the shape of the radial mode sequence. This shape turns out to be approximately symmetric around the central radial mode for RGB stars but asymmetric for core He burning stars. We computed radial mode frequencies for a sequence of red-giant models and find them to qualitatively confirm our findings. We also find that, at least in our models, the local {$\increment\nu$} is an at least as good and mostly better proxy for both the asymptotic spacing and the large separation scaled from the model density than the average {$\increment\nu$}. Finally, we investigate the signature of the evolutionary stage on {$\delta\nu$}\textsubscript{02} and quantify the mass dependency of this seismic parameter.},
  file = {/Users/Oliver/Zotero/storage/E6IJYMZ3/Kallinger et al. - 2012 - Evolutionary influences on the structure of red-gi.pdf;/Users/Oliver/Zotero/storage/RLV8KN78/ui.adsabs.harvard.edu.html},
  journal = {Astronomy and Astrophysics},
  language = {en}
}

@article{kallinger+2014,
  title = {The Connection between Stellar Granulation and Oscillation as Seen by the {{Kepler}} Mission},
  author = {Kallinger, T. and De Ridder, J. and Hekker, S. and Mathur, S. and Mosser, B. and Gruberbauer, M. and Garcia, R. A. and Karoff, C. and Ballot, J.},
  year = {2014},
  month = oct,
  volume = {570},
  pages = {A41},
  issn = {0004-6361, 1432-0746},
  doi = {10.1051/0004-6361/201424313},
  abstract = {The long and almost continuous observations by Kepler show clear evidence of a granulation background signal in a large sample of stars, which is interpreted as the surface manifestation of convection. It has been shown that its characteristic timescale and rms intensity fluctuation scale with the peak frequency (\textbackslash nu\_\{max\}) of the solar-like oscillations. Various attempts have been made to quantify the observed signal, to determine scaling relations, and to compare them to theoretical predictions. We use a probabilistic method to compare different approaches to extracting the granulation signal. We fit the power density spectra of a large set of Kepler targets, determine the granulation and global oscillation parameter, and quantify scaling relations between them. We establish that a depression in power at about \textbackslash nu\_\{max\}/2, known from the Sun and a few other main-sequence stars, is also statistically significant in red giants and that a super-Lorentzian function with two components is best suited to reproducing the granulation signal in the broader vicinity of the pulsation power excess. We also establish that the specific choice of the background model can affect the determination of \textbackslash nu\_\{max\}, introducing systematic uncertainties that can significantly exceed the random uncertainties. We find the characteristic background frequency and amplitude to tightly scale with \textbackslash nu\_\{max\} for a wide variety of stars, and quantify a mass dependency of the latter. To enable comparison with theoretical predictions, we computed effective timescales and intensity fluctuations and found them to approximately scale as \textbackslash tau\_\{eff\} \textbackslash propto g\^\{-0.85\}\textbackslash,T\^\{-0.4\} and A\_\{gran\} \textbackslash propto (g\^2M)\^\{-1/4\}, respectively. Similarly, the bolometric pulsation amplitude scales approximately as A\_\{puls\} \textbackslash propto (g\^2M)\^\{-1/3\}, which implicitly verifies a separate mass and luminosity dependence of A\_\{puls\}.},
  archivePrefix = {arXiv},
  eprint = {1408.0817},
  eprinttype = {arxiv},
  file = {/Users/Oliver/Zotero/storage/5TBAEFFQ/Kallinger et al. - 2014 - The connection between stellar granulation and osc.pdf;/Users/Oliver/Zotero/storage/2L64FXN3/1408.html},
  journal = {Astronomy \& Astrophysics},
  keywords = {Astrophysics - Solar and Stellar Astrophysics}
}

@article{kamiaka+2018,
  title = {Reliability of Stellar Inclination Estimated from Asteroseismology: Analytical Criteria, Mock Simulations, and {{Kepler}} Data Analysis},
  shorttitle = {Reliability of Stellar Inclination Estimated from Asteroseismology},
  author = {Kamiaka, Shoya and Benomar, Othman and Suto, Yasushi},
  year = {2018},
  month = sep,
  volume = {479},
  pages = {391},
  doi = {10.1093/mnras/sty1358},
  abstract = {Advances in asteroseismology of solar-like stars now provide a unique method to estimate the stellar inclination i\textsubscript{{$\star$}}. This enables to evaluate the spin-orbit angle of transiting planetary systems in a complementary fashion to the Rossiter-McLaughlin effect, a well-established method to estimate the projected spin-orbit angle {$\lambda$}. Although the asteroseismic method has been broadly applied to the Kepler data, its reliability is yet to be assessed intensively. In this work, we evaluate the accuracy of i\textsubscript{{$\star$}} from asteroseismology of solar-like stars using 3000 simulated power spectra. We find that the low-signal-to-noise ratio of the power spectra induces a systematic underestimate (overestimate) bias for stars with high (low) inclinations. We derive analytical criteria for the reliable asteroseismic estimate, which indicates that reliable measurements are possible in the range of 20\textdegree{} {$\lessequivlnt$} i\textsubscript{{$\star$}} {$\lessequivlnt$} 80\textdegree{} only for stars with high-signal-to-noise ratio. We also analyse and measure the stellar inclination of 94 Kepler main-sequence solar-like stars, among that 33 are planetary hosts. According to our reliability criteria, a third of them (nine with planets, 22 without) have accurate stellar inclination. Comparison of our asteroseismic estimate of vsin i\textsubscript{{$\star$}} against spectroscopic measurements indicates that the latter suffers from a large uncertainty possibly due to the modelling of macroturbulence, especially for stars with projected rotation speed vsin i\textsubscript{{$\star$}} {$\lessequivlnt$} 5 km s\textsuperscript{-1}. This reinforces earlier claims, and the stellar inclination estimated from the combination of measurements from spectroscopy and photometric variation for slowly rotating stars needs to be interpreted with caution.},
  file = {/Users/Oliver/Zotero/storage/7TW2F4T3/Kamiaka et al. - 2018 - Reliability of stellar inclination estimated from .pdf;/Users/Oliver/Zotero/storage/YBRJ9BXI/ui.adsabs.harvard.edu.html},
  journal = {Monthly Notices of the Royal Astronomical Society},
  language = {en},
  number = {1}
}

@article{karoff+2018,
  title = {The Influence of Metallicity on Stellar Differential Rotation and Magnetic Activity},
  author = {Karoff, Christoffer and Metcalfe, Travis S. and Santos, Angela R. G. and Montet, Benjamin T. and Isaacson, Howard and Witzke, Veronika and Shapiro, Alexander I. and Mathur, Savita and Davies, Guy R. and Lund, Mikkel N. and Garcia, Rafael A. and Brun, Allan S. and Salabert, David and Avelino, Pedro P. and {van Saders}, Jennifer and Egeland, Ricky and Cunha, Margarida S. and Campante, Tiago L. and Chaplin, William J. and Krivova, Natalie and Solanki, Sami K. and Stritzinger, Maximilian and Knudsen, Mads F.},
  year = {2018},
  month = jan,
  volume = {852},
  pages = {46},
  issn = {1538-4357},
  doi = {10.3847/1538-4357/aaa026},
  abstract = {Observations of Sun-like stars over the last half-century have improved our understanding of how magnetic dynamos, like that responsible for the 11-year solar cycle, change with rotation, mass and age. Here we show for the first time how metallicity can affect a stellar dynamo. Using the most complete set of observations of a stellar cycle ever obtained for a Sun-like star, we show how the solar analog HD 173701 exhibits solar-like differential rotation and a 7.4-year activity cycle. While the duration of the cycle is comparable to that generated by the solar dynamo, the amplitude of the brightness variability is substantially stronger. The only significant difference between HD 173701 and the Sun is its metallicity, which is twice the solar value. Therefore, this provides a unique opportunity to study the effect of the higher metallicity on the dynamo acting in this star and to obtain a comprehensive understanding of the physical mechanisms responsible for the observed photometric variability. The observations can be explained by the higher metallicity of the star, which is predicted to foster a deeper outer convection zone and a higher facular contrast, resulting in stronger variability.},
  archivePrefix = {arXiv},
  eprint = {1711.07716},
  eprinttype = {arxiv},
  file = {/Users/Oliver/Zotero/storage/PAPZIGG4/Karoff et al. - 2018 - The influence of metallicity on stellar differenti.pdf;/Users/Oliver/Zotero/storage/Y9XVSWB6/1711.html},
  journal = {The Astrophysical Journal},
  keywords = {Astrophysics - Solar and Stellar Astrophysics},
  number = {1}
}

@article{kass+raftery1995,
  title = {Bayes {{Factors}}},
  author = {Kass, Robert E. and Raftery, Adrian E.},
  year = {1995},
  month = jun,
  volume = {90},
  pages = {773--795},
  issn = {0162-1459},
  doi = {10.1080/01621459.1995.10476572},
  abstract = {In a 1935 paper and in his book Theory of Probability, Jeffreys developed a methodology for quantifying the evidence in favor of a scientific theory. The centerpiece was a number, now called the Bayes factor, which is the posterior odds of the null hypothesis when the prior probability on the null is one-half. Although there has been much discussion of Bayesian hypothesis testing in the context of criticism of P-values, less attention has been given to the Bayes factor as a practical tool of applied statistics. In this article we review and discuss the uses of Bayes factors in the context of five scientific applications in genetics, sports, ecology, sociology, and psychology. We emphasize the following points: \textbullet From Jeffreys' Bayesian viewpoint, the purpose of hypothesis testing is to evaluate the evidence in favor of a scientific theory.\textbullet Bayes factors offer a way of evaluating evidence in favor of a null hypothesis.\textbullet Bayes factors provide a way of incorporating external information into the evaluation of evidence about a hypothesis.\textbullet Bayes factors are very general and do not require alternative models to be nested.\textbullet Several techniques are available for computing Bayes factors, including asymptotic approximations that are easy to compute using the output from standard packages that maximize likelihoods.\textbullet In ``nonstandard'' statistical models that do not satisfy common regularity conditions, it can be technically simpler to calculate Bayes factors than to derive non-Bayesian significance tests.\textbullet The Schwarz criterion (or BIC) gives a rough approximation to the logarithm of the Bayes factor, which is easy to use and does not require evaluation of prior distributions.\textbullet When one is interested in estimation or prediction, Bayes factors may be converted to weights to be attached to various models so that a composite estimate or prediction may be obtained that takes account of structural or model uncertainty.\textbullet Algorithms have been proposed that allow model uncertainty to be taken into account when the class of models initially considered is very large.\textbullet Bayes factors are useful for guiding an evolutionary model-building process.\textbullet It is important, and feasible, to assess the sensitivity of conclusions to the prior distributions used.},
  file = {/Users/Oliver/Zotero/storage/L6HH76AN/01621459.1995.html},
  journal = {Journal of the American Statistical Association},
  number = {430}
}

@article{kawaler+1999,
  title = {Prospects for {{Measuring Differential Rotation}} in {{White Dwarfs}} through {{Asteroseismology}}},
  author = {Kawaler, Steven D. and Sekii, Takashi and Gough, Douglas},
  year = {1999},
  month = may,
  volume = {516},
  pages = {349},
  doi = {10.1086/307087},
  abstract = {We examine the potential of asteroseismology for exploring the internal rotation of white dwarf stars. Data from global observing campaigns have revealed a wealth of frequencies, some of which show the signature of rotational splitting. Tools developed for helioseismology to use many solar p-mode frequencies for inversion of the rotation rate with depth are adapted to the case of more limited numbers of modes of low degree. We find that the small number of available modes in white dwarfs, coupled with the similarity between the rotational-splitting kernels of the modes, renders direct inversion unstable. Accordingly, we adopt what we consider to be plausible functional forms for the differential rotation profile; this is sufficiently restrictive to enable us to carry out a useful calibration. We show examples of this technique for PG 1159 stars and pulsating DB white dwarfs. Published frequency splittings for white dwarfs are currently not accurate enough for meaningful inversions; reanalysis of existing data can provide splittings of sufficient accuracy when the frequencies of individual peaks are extracted via least-squares fitting or multipeak decompositions. We find that, when mode trapping is evident in the period spacing of g modes, the measured splittings can constrain d{$\Omega$}/dr.},
  file = {/Users/Oliver/Zotero/storage/2STMLSGW/Kawaler et al. - 1999 - Prospects for Measuring Differential Rotation in W.pdf;/Users/Oliver/Zotero/storage/QYI5R8RC/ui.adsabs.harvard.edu.html},
  journal = {The Astrophysical Journal},
  language = {en},
  number = {1}
}

@article{kawaler1988,
  title = {Angular Momentum Loss in Low-Mass Stars},
  author = {Kawaler, Steven D.},
  year = {1988},
  month = oct,
  volume = {333},
  pages = {236},
  issn = {0004-637X, 1538-4357},
  doi = {10.1086/166740},
  abstract = {A general expression for angular momentum loss by magnetic stellar winds is applied to evolutionary stellar models to see if such wind models can account for the total loss of angular momentum in low-mass stars. Reasonable wind models do indeed extract sufficient angular momentum for two limiting cases of the internal angular momentum distribution. Most of the angular momentum is lost in the vicinity of the zero-age main sequence. These computations allows testing of models of angular momentum loss by comparison with a variety of observations. The existence of very rapidly rotating stars in young clusters implies that low-mass stars are formed with a large spread in angular momentum. The high efficiency of angular momentum loss through magnetic stellar winds causes the rotation velocity to become less dependent on initial angular momentum (J0) with time; by 3 x 108 yr, the rotation velocity becomes independent of J0. This results in a decrease with time in the spread of rotation velocities as a function of stellar mass in young clusters. Data on the rotation of G and K stars in young clusters suggests that initially only the outer convective envelope in low-mass stars is spun down, as suggested by Stauffer and Hartmann. But by 100 million yr, essentially the entire stellar interior has spun down.},
  file = {/Users/Oliver/Zotero/storage/J2LK97WU/Kawaler - 1988 - Angular momentum loss in low-mass stars.pdf},
  journal = {The Astrophysical Journal},
  language = {en}
}

@article{kennedy+gongteam1994,
  title = {{{GONG}}, {{A Global Network}} of {{Automated Solar Telescopes}}},
  author = {Kennedy, James R. and {GONG Team}},
  year = {1994},
  volume = {55},
  pages = {188},
  abstract = {Not Available},
  file = {/Users/Oliver/Zotero/storage/UHIRZGR3/Kennedy and GONG Team - 1994 - GONG, A Global Network of Automated Solar Telescop.pdf}
}

@article{khan+2018,
  title = {The {{Red}}-Giant {{Branch Bump Revisited}}: {{Constraints}} on {{Envelope Overshooting}} in a {{Wide Range}} of {{Masses}} and {{Metallicities}}},
  shorttitle = {The {{Red}}-Giant {{Branch Bump Revisited}}},
  author = {Khan, Saniya and Hall, Oliver J. and Miglio, Andrea and Davies, Guy R. and Mosser, Beno{\^i}t and Girardi, L{\'e}o and Montalb{\'a}n, Josefina},
  year = {2018},
  month = jun,
  volume = {859},
  pages = {156},
  doi = {10.3847/1538-4357/aabf90},
  abstract = {The red-giant branch bump provides valuable information for the investigation of the internal structure of low-mass stars. Because current models are unable to accurately predict the occurrence and efficiency of mixing processes beyond convective boundaries, one can use the luminosity of the bump\textemdash a diagnostic of the maximum extension of the convective envelope during the first-dredge up\textemdash as a calibrator for such processes. By combining asteroseismic and spectroscopic constraints, we expand the analysis of the bump to masses and metallicities beyond those previously accessible using globular clusters. Our data set comprises nearly 3000 red-giant stars observed by Kepler and with APOGEE spectra. Using statistical mixture models, we are able to detect the bump in the average seismic parameters {$\nu$} \textsubscript{max} and \< \{\{{$\increment$} \}\}{$\nu$} \> , and show that its observed position reveals general trends with mass and metallicity in line with expectations from models. Moreover, our analysis indicates that standard stellar models underestimate the depth of efficiently mixed envelopes. The inclusion of significant overshooting from the base of the convective envelope, with an efficiency that increases with decreasing metallicity, allows us to reproduce the observed location of the bump. Interestingly, this trend was also reported in previous studies of globular clusters.},
  file = {/Users/Oliver/Zotero/storage/FLVG6ZGD/Khan et al. - 2018 - The Red-giant Branch Bump Revisited Constraints o.pdf;/Users/Oliver/Zotero/storage/K8SHYA7F/abstract.html},
  journal = {The Astrophysical Journal},
  language = {en},
  number = {2}
}

@article{khan+2019,
  title = {New Light on the {{Gaia DR2}} Parallax Zero-Point: Influence of the Asteroseismic Approach, in and beyond the {{Kepler}} Field},
  shorttitle = {New Light on the {{Gaia DR2}} Parallax Zero-Point},
  author = {Khan, S. and Miglio, A. and Mosser, B. and Arenou, F. and Belkacem, K. and Brown, A. G. A. and Katz, D. and Casagrande, L. and Chaplin, W. J. and Davies, G. R. and Rendle, B. M. and Rodrigues, T. S. and Bossini, D. and {Cantat-Gaudin}, T. and Elsworth, Y. P. and Girardi, L. and North, T. S. H. and Vallenari, A.},
  year = {2019},
  month = aug,
  volume = {628},
  pages = {A35},
  issn = {0004-6361},
  doi = {10.1051/0004-6361/201935304},
  abstract = {The importance of studying the Gaia DR2 parallax zero-point by external means was underlined by the articles that accompanied the release, and initiated by several works making use of Cepheids, eclipsing binaries, and asteroseismology. Despite a very efficient elimination of basic-angle variations, a small fluctuation remains and shows up as a small offset in the Gaia DR2 parallaxes. By combining astrometric, asteroseismic, spectroscopic, and photometric constraints, we undertake a new analysis of the Gaia parallax offset for nearly 3000 red-giant branch (RGB) and 2200 red clump (RC) stars observed by Kepler, as well as about 500 and 700 red giants (all either in the RGB or RC phase) selected by the K2 Galactic Archaeology Program in campaigns 3 and 6. Engaging in a thorough comparison of the astrometric and asteroseismic parallaxes, we are able to highlight the influence of the asteroseismic method, and measure parallax offsets in the Kepler field that are compatible with independent estimates from literature and open clusters. Moreover, adding the K2 fields to our investigation allows us to retrieve a clear illustration of the positional dependence of the zero-point, in general agreement with the information provided by quasars. Lastly, we initiate a two-step methodology to make progress in the simultaneous calibration of the asteroseismic scaling relations and of the Gaia DR2 parallax offset, which will greatly benefit from the gain in precision with the third data release of Gaia.},
  file = {/Users/Oliver/Zotero/storage/EE2ZSNP7/Khan et al. - 2019 - New light on the Gaia DR2 parallax zero-point inf.pdf;/Users/Oliver/Zotero/storage/WUY3ZQQK/abstract.html},
  journal = {Astronomy and Astrophysics},
  language = {en}
}

@article{kiefer+2016,
  title = {Stellar Magnetic Activity and Variability of Oscillation Parameters - {{An}} Investigation of 24 Solar-like Stars Observed by {{Kepler}}},
  author = {Kiefer, Ren{\'e} and Schad, Ariane and Davies, Guy and Roth, Markus},
  year = {2016},
  month = nov,
  abstract = {Context. The Sun and solar-like stars undergo activity cycles for which the underlying mechanisms are not well understood. The oscillations of the Sun are known to vary with its activity cycle and these changes provide diagnostics on the conditions below the photosphere. Kepler has detected oscillations in hundreds of solar-like stars but as of yet, no widespread detection of signatures of magnetic activity cycles in the oscillation parameters of these stars have been reported. Aims. We analyse the photometric short cadence Kepler time series of a set of 24 solar-like stars, which were observed for at least 960 days each, with the aim to find signatures of stellar magnetic activity in the oscillation parameters. Methods. We analyse the temporal evolution of oscillation parameters by measuring mode frequency shifts, changes in the height of the p-mode envelope, as well as granulation time scales. Results. For 23 of the 24 investigated stars, we find significant frequency shifts in time. We present evidence for magnetic activity in six of them. We find that the amplitude of the frequency shifts decreases with stellar age and rotation period. For the most prominent example, KIC 8006161, we find that, similar to the solar case, frequency shifts are smallest for the lowest and largest for the highest p-mode frequencies. Conclusions. These findings show that magnetic activity can be routinely observed in the oscillation parameters for solar-like stars, which opens up the possibility to place the solar activity cycle in the context of other stars by asteroseismology.},
  archivePrefix = {arXiv},
  eprint = {1611.02029},
  eprinttype = {arxiv},
  file = {/Users/Oliver/Zotero/storage/QJ44K6AP/Kiefer et al. - 2016 - Stellar magnetic activity and variability of oscil.pdf;/Users/Oliver/Zotero/storage/PH49NHF7/1611.html},
  journal = {arXiv:1611.02029 [astro-ph]},
  keywords = {Astrophysics - Solar and Stellar Astrophysics},
  primaryClass = {astro-ph}
}

@article{kiefer+roth2018,
  title = {The {{Effect}} of {{Toroidal Magnetic Fields}} on {{Solar Oscillation Frequencies}}},
  author = {Kiefer, Ren{\'e} and Roth, Markus},
  year = {2018},
  month = feb,
  volume = {854},
  pages = {74},
  issn = {0004-637X},
  doi = {10.3847/1538-4357/aaa3f7},
  abstract = {Solar oscillation frequencies change with the level of magnetic activity. Localizing subsurface magnetic field concentrations in the Sun with helioseismology will help us to understand the solar dynamo. Because the magnetic fields are not considered in standard solar models, adding them to the basic equations of stellar structure changes the eigenfunctions and eigenfrequencies. We use quasi-degenerate
perturbation theory to calculate the effect of toroidal magnetic fields on solar oscillation mean multiplet frequencies for six field
configurations. In our calculations, we consider both the direct effect of the magnetic field, which describes the coupling of modes, and the indirect effect, which accounts for changes in stellar structure due to the magnetic field. We limit our calculations to self-coupling of modes. We find that the magnetic field affects the multiplet frequencies in a way that depends on the location and the geometry of the field inside the Sun. Comparing our theoretical results with observed shifts, we find that strong tachocline fields cannot be responsible for the observed frequency shifts of p modes over the solar cycle. We also find that part of the surface effect in helioseismic oscillation frequencies might be attributed to magnetic fields in the outer layers of the Sun. The theory presented here is also applicable to models of solar-like stars and their oscillation frequencies.},
  file = {/Users/Oliver/Zotero/storage/UHIZC98C/Kiefer and Roth - 2018 - The Effect of Toroidal Magnetic Fields on Solar Os.pdf},
  journal = {The Astrophysical Journal},
  keywords = {asteroseismology,dynamo,methods: analytical,methods: numerical,Sun: helioseismology,Sun: magnetic fields}
}

@article{kjeldsen+1995,
  title = {Solarlike Oscillations in {$\eta$} {{Boo}}},
  author = {Kjeldsen, Hans and Bedding, Timothy R. and Viskum, Michael and Frandsen, Soren},
  year = {1995},
  month = mar,
  volume = {109},
  pages = {1313--1319},
  issn = {0004-6256},
  doi = {10.1086/117363},
  abstract = {We have observed evidence for p-mode oscillations in the GOIV star eta Boo (V = 2.68). This represents the first clear evidence of solarlike oscillations in a star other than the Sun. We used a new technique which measures fluctuations in the temperature of the star via their effect on the equivalent widths of the Balmer lines. The observations were obtained over six nights with the 2.5 m Nordic Optical Telescope on La Palma and consist of 12 684 low-dispersion spectra. In the power spectrum of the equivalent-width measurements, we find an excess of power at frequencies aroun 850 microHz (period 20 min) which consist of a regular series of peaks with a spacing of Delta nu = 40.3 micro Hz. We identify 13 oscillation modes, with frequency separations in agreement with theoretical expectations. Similar observations of the daytime sky show the 5 min solar oscillations at the expected frequencies.},
  file = {/Users/Oliver/Zotero/storage/ADTWHFNA/Kjeldsen et al. - 1995 - Solarlike oscillations in η Boo.pdf},
  journal = {The Astronomical Journal},
  keywords = {Amplitudes,Balmer Series,Data Correlation,Frequencies,G Stars,Power Spectra,Spectral Line Width,Spectrum Analysis,Stellar Oscillations,Stellar Temperature}
}

@article{kjeldsen+2003,
  title = {Confirmation of {{Solar}}-like {{Oscillations}} in {$\eta$} {{Bootis}}},
  author = {Kjeldsen, H. and Bedding, T. R. and Baldry, I. K. and Bruntt, H. and Butler, R. P. and Fischer, D. A. and Frandsen, S. and Gates, E. L. and Grundahl, F. and Lang, K. and Marcy, G. W. and Misch, A. and Vogt, S. S.},
  year = {2003},
  month = sep,
  volume = {126},
  pages = {1483--1488},
  issn = {0004-6256},
  doi = {10.1086/377315},
  abstract = {We obtained time-series spectroscopy of the G0 subgiant {$\eta$} Boo in an attempt to confirm the solar-like oscillations reported by Kjeldsen and coworkers in 1995. We recorded 1843 spectra over six consecutive nights with the Nordic Optical Telescope, which we used to measure equivalent widths of strong temperature-sensitive lines. We also measured
velocities from 1989 spectra obtained through an iodine reference cell at Lick Observatory over 56 nights that were badly affected by weather. Our analysis also included velocity measurements published by Brown and coworkers and the original Kjeldsen equivalent width measurements. All four data sets show power excesses consistent with oscillations, although with a range of amplitudes that presumably reflects the stochastic nature of the excitation. The highest peaks show regularity with a large separation of {$\Delta\nu$}=40.4 {$\mu$}Hz, and we identify 21
oscillation frequencies from the combined data.},
  file = {/Users/Oliver/Zotero/storage/SMXGH55D/Kjeldsen et al. - 2003 - Confirmation of Solar-like Oscillations in η Booti.pdf},
  journal = {The Astronomical Journal},
  keywords = {Stars: Individual: Constellation Name: η Bootis,Stars: Oscillations,Techniques: Radial Velocities}
}

@article{kjeldsen+bedding1995,
  title = {Amplitudes of Stellar Oscillations: The Implications for Asteroseismology.},
  shorttitle = {Amplitudes of Stellar Oscillations},
  author = {Kjeldsen, H. and Bedding, T. R.},
  year = {1995},
  month = jan,
  volume = {293},
  pages = {87},
  abstract = {There are no good predictions for the amplitudes expected from solar-like oscillations in other stars. In the absence of a definitive model for convection, which is thought to be the mechanism that excites these oscillations, the amplitudes for both velocity and luminosity measurements must be estimated by scaling from the Sun. In the case of luminosity measurements, even this is difficult because of disagreement over the solar amplitude. This last point has lead us to investigate whether the luminosity amplitude of oscillations {$\delta$}L/L can be derived from the velocity amplitude (v\_osc\_). Using linear theory and observational data, we show that p-mode oscillations in a large sample of pulsating stars satisfy ({$\delta$}L/L)\_bol\_\{prop.to\} v\_osc\_/T\_eff\_. Using this relationship, together with the best estimate of v\_osc\_,\textsubscript{sun}\_=(23.4+/-1.4)cm/s, we estimate the luminosity amplitude of solar oscillations at 550nm to be {$\delta$}L/L=(4.7+/-0.3)ppm. Next we discuss how to scale the amplitude of solar-like (i.e., convectively-powered) oscillations from the Sun to other stars. The only predictions come from model calculations by Christensen-Dalsgaard \& Frandsen (1983, Sol. Phys. 82, 469). However, their grid of stellar models is not dense enough to allow amplitude predictions for an arbitrary star. Nevertheless, although convective theory is complicated, we might expect that the general properties of convection - including oscillation amplitudes - should change smoothly through the colour-magnitude diagram. Indeed, we find that the velocity amplitudes predicted by the model calculations are well fitted by the relation v\_osc\_\{prop.to\}L/M. These two relations allow us to predict both the velocity and luminosity amplitudes of solar-like oscillations in any given star. We compare these predictions with published observations and evaluate claims for detections that have appeared in the literature. We argue that there is not yet good evidence for solar-like oscillations in any star except the Sun. For solar-type stars (e.g., {$\alpha$} Cen A and {$\beta$} Hyi), observations have not yet reached sufficient sensitivity to detect the amplitudes we predict. For some F-type stars, namely Procyon and several members of M67, detection sensitivities 30-40\% below the predicted amplitudes have been achieved. We conclude that these stars must oscillate with amplitudes less than has generally been assumed.},
  file = {/Users/Oliver/Zotero/storage/UCCFQKAF/Kjeldsen and Bedding - 1995 - Amplitudes of stellar oscillations the implicatio.pdf;/Users/Oliver/Zotero/storage/8PBWDRY5/abstract.html},
  journal = {Astronomy and Astrophysics},
  language = {en}
}

@article{kjeldsen+frandsen1992,
  title = {High-Precision Time-Resolved {{CCD}} Photometry},
  author = {Kjeldsen, Hans and Frandsen, Soren},
  year = {1992},
  month = jun,
  volume = {104},
  pages = {413--434},
  issn = {0004-6280},
  doi = {10.1086/133014},
  abstract = {High-precision time-resolved photometry and detection of low-amplitude stellar oscillations are limited in precision by many factors. The noise terms for a typical time-series observation contain observational noise and errors as well as instrumental noise and reduction noise. This paper describes some of the problems related to high-precision photometry, especially focusing on CCD photometry both on focused stars (in semi- and noncrowded fields) and defocused field stars. It is shown that atmospheric transparency variations and instrumental drift are the main noise sources at low frequencies (below 1-2 mHz), and that CCD
photometry is the best way of doing differential measurements in order to detect oscillations at low frequencies. The theoretical description of noise and problems in high-precision photometry is compared with CCD time-series observations in a noncrowded test field observed with the Danish 1.5-m telescope at ESO La Silla, Chile in 1990. In addition, observations of defocused double stars observed with the Nordic Optical Telescope in 1991 are described.},
  file = {/Users/Oliver/Zotero/storage/6W38NSPH/Kjeldsen and Frandsen - 1992 - High-precision time-resolved CCD photometry.pdf},
  journal = {Publications of the Astronomical Society of the Pacific},
  keywords = {Astronomical Photometry,Double Stars,Electrophotometers,Point Spread Functions,Precision,Signal To Noise Ratios,Stellar Magnitude,Stellar Oscillations,Temporal Resolution}
}

@article{kjeldsen+frandsen1992a,
  title = {High-Precision Time-Resolved {{CCD}} Photometry},
  author = {Kjeldsen, Hans and Frandsen, Soren},
  year = {1992},
  month = jun,
  volume = {104},
  pages = {413--434},
  issn = {0004-6280},
  doi = {10.1086/133014},
  abstract = {High-precision time-resolved photometry and detection of low-amplitude stellar oscillations are limited in precision by many factors. The noise terms for a typical time-series observation contain observational noise and errors as well as instrumental noise and reduction noise. This paper describes some of the problems related to high-precision photometry, especially focusing on CCD photometry both on focused stars (in semi- and noncrowded fields) and defocused field stars. It is shown that atmospheric transparency variations and instrumental drift are the main noise sources at low frequencies (below 1-2 mHz), and that CCD
photometry is the best way of doing differential measurements in order to detect oscillations at low frequencies. The theoretical description of noise and problems in high-precision photometry is compared with CCD time-series observations in a noncrowded test field observed with the Danish 1.5-m telescope at ESO La Silla, Chile in 1990. In addition, observations of defocused double stars observed with the Nordic Optical Telescope in 1991 are described.},
  file = {/Users/Oliver/Zotero/storage/H5XRMGIA/Kjeldsen and Frandsen - 1992 - High-precision time-resolved CCD photometry.pdf},
  journal = {Publications of the Astronomical Society of the Pacific},
  keywords = {Astronomical Photometry,Double Stars,Electrophotometers,Point Spread Functions,Precision,Signal To Noise Ratios,Stellar Magnitude,Stellar Oscillations,Temporal Resolution}
}

@inproceedings{kluyver+2016,
  title = {Jupyter {{Notebooks}} \textendash{} a Publishing Format for Reproducible Computational Workflows},
  booktitle = {Positioning and {{Power}} in {{Academic Publishing}}: {{Players}}, {{Agents}} and {{Agendas}}},
  author = {Kluyver, Thomas and {Ragan-Kelley}, Benjamin and P{\'e}rez, Fernando and Granger, Brian and Bussonnier, Matthias and Frederic, Jonathan and Kelley, Kyle and Hamrick, Jessica and Grout, Jason and Corlay, Sylvain and Ivanov, Paul and Avila, Dami{\'a}n and Abdalla, Safia and Willing, Carol and {Jupyter development team}},
  editor = {Loizides, Fernando and Scmidt, Birgit},
  year = {2016},
  pages = {87--90},
  publisher = {{IOS Press}},
  doi = {doi:10.3233/978-1-61499-649-1-87},
  abstract = {It is increasingly necessary for researchers in all fields to write computer code, and in order to reproduce research results, it is important that this code is published. We present Jupyter notebooks, a document format for publishing code, results and explanations in a form that is both readable and executable. We discuss various tools and use cases for notebook documents.},
  collaborator = {Kluyver, Thomas and {Ragan-Kelley}, Benjamin and P{\'e}rez, Fernando and Granger, Brian and Bussonnier, Matthias and Frederic, Jonathan and Kelley, Kyle and Hamrick, Jessica and Grout, Jason and Corlay, Sylvain and Ivanov, Paul and Avila, Dami{\'a}n and Abdalla, Safia and Willing, Carol and {Jupyter development team} and Loizides, Fernando and Scmidt, Birgit},
  copyright = {cc\_by\_4},
  file = {/Users/Oliver/Zotero/storage/9MLVELMU/Kluyver et al. - 2016 - Jupyter Notebooks – a publishing format for reprod.pdf;/Users/Oliver/Zotero/storage/9SL5BC58/403913.html},
  language = {en}
}

@article{koch+2010,
  title = {Kepler {{Mission Design}}, {{Realized Photometric Performance}}, and {{Early Science}}},
  author = {Koch, David G. and Borucki, William J. and Basri, Gibor and Batalha, Natalie M. and Brown, Timothy M. and Caldwell, Douglas and {Christensen-Dalsgaard}, J{\o}rgen and Cochran, William D. and DeVore, Edna and Dunham, Edward W. and Gautier, Thomas N. and Geary, John C. and Gilliland, Ronald L. and Gould, Alan and Jenkins, Jon and Kondo, Yoji and Latham, David W. and Lissauer, Jack J. and Marcy, Geoffrey and Monet, David and Sasselov, Dimitar and Boss, Alan and Brownlee, Donald and Caldwell, John and Dupree, Andrea K. and Howell, Steve B. and Kjeldsen, Hans and Meibom, S{\o}ren and Morrison, David and Owen, Tobias and Reitsema, Harold and Tarter, Jill and Bryson, Stephen T. and Dotson, Jessie L. and Gazis, Paul and Haas, Michael R. and Kolodziejczak, Jeffrey and Rowe, Jason F. and Cleve, Van and E, Jeffrey and Allen, Christopher and Chandrasekaran, Hema and Clarke, Bruce D. and Li, Jie and Quintana, Elisa V. and Tenenbaum, Peter and Twicken, Joseph D. and Wu, Hayley},
  year = {2010},
  month = apr,
  volume = {713},
  pages = {L79},
  doi = {10.1088/2041-8205/713/2/L79},
  abstract = {The Kepler Mission, launched on 2009 March 6, was designed with the explicit capability to detect Earth-size planets in the habitable zone of solar-like stars using the transit photometry method. Results from just 43 days of data along with ground-based follow-up observations have identified five new transiting planets with measurements of their masses, radii, and orbital periods. Many aspects of stellar astrophysics also benefit from the unique, precise, extended, and nearly continuous data set for a large number and variety of stars. Early results for classical variables and eclipsing stars show great promise. To fully understand the methodology, processes, and eventually the results from the mission, we present the underlying rationale that ultimately led to the flight and ground system designs used to achieve the exquisite photometric performance. As an example of the initial photometric results, we present variability measurements that can be used to distinguish dwarf stars from red giants.},
  file = {/Users/Oliver/Zotero/storage/VAEBXR3R/Koch et al. - 2010 - Kepler Mission Design, Realized Photometric Perfor.pdf;/Users/Oliver/Zotero/storage/KPKPCF2D/ui.adsabs.harvard.edu.html},
  journal = {The Astrophysical Journal},
  language = {en},
  number = {2}
}

@article{kochukhov+2016,
  title = {Surface Magnetism of Cool Stars},
  author = {Kochukhov, O. and Petit, P. and Strassmeier, K. G. and Carroll, T. A. and Fares, R. and Folsom, C. P. and Jeffers, S. V. and Korhonen, H. and Monnier, J. D. and Morin, J. and Rosen, L. and Roettenbacher, R. M. and Shulyak, D.},
  year = {2016},
  month = dec,
  abstract = {Magnetic fields are essential ingredients of many physical processes in the interiors and envelopes of cool stars. Yet their direct detection and characterisation is notoriously difficult, requiring high-quality observations and advanced analysis techniques. Significant progress has been recently achieved by several types of direct magnetic field studies on the surfaces of cool active stars. In particular, complementary techniques of the field topology mapping with polarisation data and total magnetic flux measurements from intensity spectra have been systematically applied to different classes of active stars leading to interesting and occasionally controversial results. In this paper we summarise the current status of direct magnetic field studies of cool stars, and investigations of surface inhomogeneities caused by the field, based on the material presented at the Cool Stars 19 splinter session.},
  archivePrefix = {arXiv},
  eprint = {1612.03388},
  eprinttype = {arxiv},
  file = {/Users/Oliver/Zotero/storage/35RQQVSK/Kochukhov et al. - 2016 - Surface magnetism of cool stars.pdf;/Users/Oliver/Zotero/storage/ENNHQ8V8/1612.html},
  journal = {arXiv:1612.03388 [astro-ph]},
  keywords = {Astrophysics - Solar and Stellar Astrophysics},
  primaryClass = {astro-ph}
}

@article{kounkel+2018,
  title = {{{VLBA Observations}} of {{Strong Anisotripic Radio Scattering Toward}} the {{Orion Nebula}}},
  author = {Kounkel, Marina and Hartmann, Lee and Loinard, Laurent and Mioduszewski, Amy J. and Rodr{\'i}guez, Luis F. and {Ortiz-Le{\'o}n}, Gisela N. and Johnson, Michael D. and Torres, Rosa M. and Brice{\~n}o, Cesar},
  year = {2018},
  month = may,
  volume = {155},
  pages = {218},
  doi = {10.3847/1538-3881/aabc58},
  abstract = {We present observations of VLBA 20, a radio source found toward the edge of the Orion Nebula Cluster (ONC). Nonthermal emission dominates the spectral energy distribution of this object from the radio to mid-infrared regime, suggesting that VLBA 20 is extragalactic. This source is heavily scattered in the radio regime. Very Long Baseline Array observations resolve it to {$\sim$}34 \texttimes{} 19 mas at 5 GHz, and the wavelength dependence of the scattering disk is consistent with {$\nu$} \textsuperscript{-2} at other frequencies. The origin of the scattering is most likely the ionized X-ray emitting gas from the winds of the most massive stars of the ONC. The scattering is highly anisotropic, with the axis ratio of 2:1, higher than what is typically observed toward other sources.},
  file = {/Users/Oliver/Zotero/storage/FIDJXXNI/Kounkel et al. - 2018 - VLBA Observations of Strong Anisotripic Radio Scat.pdf;/Users/Oliver/Zotero/storage/YRZUTI2P/ui.adsabs.harvard.edu.html},
  journal = {The Astronomical Journal},
  language = {en},
  number = {5}
}

@article{kraft1967,
  title = {Studies of {{Stellar Rotation}}. {{V}}. {{The Dependence}} of {{Rotation}} on {{Age}} among {{Solar}}-{{Type Stars}}},
  author = {Kraft, Robert P.},
  year = {1967},
  month = nov,
  volume = {150},
  pages = {551},
  issn = {0004-637X},
  doi = {10.1086/149359},
  abstract = {The rotational velocities of a large sample of field stars with spectral types between F2 IV, V and G3 IV, V have been obtained from coude' spectrograms of resolution about 6 km/sec. It is shown that the average rotational velocity is higher among those with Ca ii emission than among those without. Since there is strong evidence that stars with Ca ii emission are younger, on the average, than most solar-type stars, a picture is advanced in which rotation declines with advancing age. It is proposed that magnetically coupled winds, similar to the solar wind, are responsible for this deceleration even after a star takes up residence on the main sequence. The winds are presumably generated only in stars which have subsurface hydrogen convection zones and concomitant chromospheres. Estimates of rotational velocity among solar-type stars in the Hyades and Pleiades are given which confirm this general picture. It is shown that the mean rotation in the Pleiades is highest of all groups considered and averages about 40 km/sec for stars of mass 1.20 o. The time scale for reduction by a factor of 2 of the rotational velocities of Pleiades stars is equal to the age of the Hyades, about 4 X 108 years.},
  file = {/Users/Oliver/Zotero/storage/N9TNCWAH/Kraft - 1967 - Studies of Stellar Rotation. V. The Dependence of .pdf;/Users/Oliver/Zotero/storage/MBFTJXUP/abstract.html},
  journal = {The Astrophysical Journal},
  language = {en}
}

@article{kunder+2017,
  title = {The {{Radial Velocity Experiment}} ({{RAVE}}): {{Fifth Data Release}}},
  shorttitle = {The {{Radial Velocity Experiment}} ({{RAVE}})},
  author = {Kunder, Andrea and Kordopatis, Georges and Steinmetz, Matthias and Zwitter, Toma{\v z} and McMillan, Paul J. and Casagrande, Luca and Enke, Harry and Wojno, Jennifer and Valentini, Marica and Chiappini, Cristina and Matijevi{\v c}, Gal and Siviero, Alessandro and {de Laverny}, Patrick and {Recio-Blanco}, Alejandra and Bijaoui, Albert and Wyse, Rosemary F. G. and Binney, James and Grebel, E. K. and Helmi, Amina and Jofre, Paula and Antoja, Teresa and Gilmore, Gerard and Siebert, Arnaud and Famaey, Benoit and Bienaym{\'e}, Olivier and Gibson, Brad K. and Freeman, Kenneth C. and Navarro, Julio F. and Munari, Ulisse and Seabroke, George and Anguiano, Borja and {\v Z}erjal, Maru{\v s}a and Minchev, Ivan and Reid, Warren and {Bland-Hawthorn}, Joss and Kos, Janez and Sharma, Sanjib and Watson, Fred and Parker, Quentin A. and Scholz, Ralf-Dieter and Burton, Donna and Cass, Paul and Hartley, Malcolm and Fiegert, Kristin and Stupar, Milorad and Ritter, Andreas and Hawkins, Keith and Gerhard, Ortwin and Chaplin, W. J. and Davies, G. R. and Elsworth, Y. P. and Lund, M. N. and Miglio, A. and Mosser, B.},
  year = {2017},
  month = feb,
  volume = {153},
  pages = {75},
  issn = {0004-6256},
  doi = {10.3847/1538-3881/153/2/75},
  abstract = {Data Release 5 (DR5) of the Radial Velocity Experiment (RAVE) is the fifth data release from a magnitude-limited (9{$<$} I{$<$} 12) survey of stars randomly selected in the Southern Hemisphere. The RAVE
medium-resolution spectra (R\texttildelow{} 7500) covering the Ca-triplet region (8410-8795 \AA ) span the complete time frame from the start of
RAVE observations in 2003 to their completion in 2013. Radial velocities from 520,781 spectra of 457,588 unique stars are presented, of which 255,922 stellar observations have parallaxes and proper motions from the Tycho-Gaia astrometric solution in Gaia DR1. For our main DR5 catalog, stellar parameters (effective temperature, surface gravity, and overall metallicity) are computed using the RAVE DR4 stellar pipeline, but calibrated using recent K2 Campaign 1 seismic gravities and Gaia benchmark stars, as well as results obtained from high-resolution studies. Also included are temperatures from the Infrared Flux Method, and we provide a catalog of red giant stars in the dereddened color \{(J-\{Ks\})\}0 interval (0.50, 0.85) for which the gravities were calibrated based only on seismology. Further data products for subsamples of the RAVE stars include individual abundances for Mg, Al, Si, Ca, Ti, Fe, and Ni, and distances found using isochrones. Each RAVE spectrum is complemented by an error spectrum, which has been used to determine uncertainties on the parameters. The data can be accessed via the RAVE Web site or the VizieR database.},
  file = {/Users/Oliver/Zotero/storage/JZRFSIIK/Kunder et al. - 2017 - The Radial Velocity Experiment (RAVE) Fifth Data .pdf},
  journal = {The Astronomical Journal},
  keywords = {catalogs,Galaxy: abundances,Galaxy: kinematics and dynamics,Galaxy: stellar content,stars: abundances,surveys}
}

@article{lagarde+2017,
  title = {Population Synthesis to Constrain {{Galactic}} and {{Stellar Physics}}- {{I}}- {{Determining}} Age and Mass of Thin-Disc Red-Giant Stars},
  author = {Lagarde, N. and Robin, A. C. and Reyl{\'e}, C. and Nasello, G.},
  year = {2017},
  month = feb,
  abstract = {The cornerstone mission Gaia, together with complementary surveys, will revolutionize our understanding of the formation and history of our Galaxy, providing accurate stellar masses, radii, ages, distances, as well as chemical properties for a very large sample of stars across different Galactic stellar populations.Using an improved population synthesis approach and new stellar evolution models we attempt to evaluate the possibility of deriving ages and masses of clump stars from their chemical properties.A new version of the Besancon Galaxy model (BGM) uses new stellar evolutionary tracks computed with STAREVOL.These provide chemical and seismic properties from the PMS to the early-AGB.For the first time, the BGM can explore the effects of an extra-mixing occurring in red-giant stars.In particular we focus on the effects of thermohaline instability on chemical properties as well as on the determination of stellar ages and masses using the surface [C/N] abundance ratio.The impact of extra-mixing on 3He, 12C/13C, N, and [C/N] abundances along the giant branch is quantified.We underline the crucial contribution of asteroseismology to discriminate between evolutionary states of field giants belonging to the Galactic disc.The inclusion of thermohaline instability has a significant impact on 12C/13C,3He as well as on the [C/N] values.We show the efficiency of thermohaline mixing at different metallicities and its influence on the determined stellar mass and age from the observed [C/N] ratio.We then propose simple relations to determine ages and masses from chemical abundances according to these models.We emphasize the usefulness of population synthesis tools to test stellar models and transport processes inside stars.We show that transport processes occurring in red-giant stars should be taken into account in the determination of ages for future Galactic archaeology studies.(abridged)},
  archivePrefix = {arXiv},
  eprint = {1702.01769},
  eprinttype = {arxiv},
  file = {/Users/Oliver/Zotero/storage/IUU3TT26/Lagarde et al. - 2017 - Population synthesis to constrain Galactic and Ste.pdf;/Users/Oliver/Zotero/storage/GI2RUNKQ/1702.html},
  journal = {arXiv:1702.01769 [astro-ph]},
  keywords = {Astrophysics - Astrophysics of Galaxies,Astrophysics - Solar and Stellar Astrophysics},
  primaryClass = {astro-ph}
}

@article{lanzafame+2018,
  title = {Gaia {{Data Release}} 2: {{Rotational}} Modulation in Late-Type Dwarfs},
  shorttitle = {Gaia {{Data Release}} 2},
  author = {Lanzafame, A. C. and Distefano, E. and Messina, S. and Pagano, I. and Lanza, A. F. and Eyer, L. and Guy, L. P. and Rimoldini, L. and {Lecoeur-Taibi}, I. and Holl, B. and {de Fombelle}, M. Audard G. J. and Nienartowicz, K. and Marchal, O. and Mowlavi, N.},
  year = {2018},
  month = aug,
  volume = {616},
  pages = {A16},
  issn = {0004-6361, 1432-0746},
  doi = {10.1051/0004-6361/201833334},
  abstract = {We present the methods devised to identify the BY Dra variables candidates in Gaia DR2 and infer their variability parameters. BY Dra candidates are pre-selected from their position in the HR diagram, built from Gaia parallaxes, \$G\$ magnitudes, and \$(G\_\{BP\} - G\_\{RP\})\$ colours. Since the time evolution of the stellar active region can disrupt the coherence of the signal, segments not much longer than their expected evolution timescale are extracted from the entire photometric time-series and period search algorithms are applied to each segment. For the Gaia DR2, we select sources having similar period in at least two segments as candidates BY Dra. Results are further filtered considering the time series phase coverage and the expected approximate light curve shape. Gaia DR2 includes rotational periods and modulation amplitudes of 147 535 BY Dra candidates. The data unveil the existence of two populations with distinctive period and amplitude distributions. The sample covers 38\% of the whole sky when divided in bins (HEALPix) of \$\textbackslash approx\$0.84 square degrees and we estimate that represents 0.7 -- 5 \% of all BY Dra stars potentially detectable by Gaia. The preliminary data contained in Gaia DR2 illustrate the vast and unique information that the mission is going to provide on stellar rotation and magnetic activity. This information, complemented by Gaia exquisite parallaxes, proper motions, and astrophysical parameter, is opening new and unique perspectives for our understanding of the evolution of stellar angular momentum and dynamo action.},
  archivePrefix = {arXiv},
  eprint = {1805.00421},
  eprinttype = {arxiv},
  file = {/Users/Oliver/Zotero/storage/VNQ7QMR4/Lanzafame et al. - 2018 - Gaia Data Release 2 Rotational modulation in late.pdf;/Users/Oliver/Zotero/storage/5M7PDKAM/1805.html},
  journal = {Astronomy \& Astrophysics},
  keywords = {Astrophysics - Solar and Stellar Astrophysics}
}

@article{leavitt+pickering1912,
  title = {Periods of 25 {{Variable Stars}} in the {{Small Magellanic Cloud}}},
  author = {Leavitt, Henrietta S. and Pickering, Edward C.},
  year = {1912},
  volume = {173},
  pages = {1--3},
  journal = {Harvard College Observatory Circular}
}

@article{lebreton+2014,
  title = {How Accurate Are Stellar Ages Based on Stellar Models?. {{I}}. {{The}} Impact of Stellar Models Uncertainties},
  shorttitle = {How Accurate Are Stellar Ages Based on Stellar Models?},
  author = {Lebreton, Y. and Goupil, M. J. and Montalb{\'a}n, J.},
  year = {2014},
  month = nov,
  volume = {65},
  pages = {99--176},
  address = {{eprint: arXiv:1410.5336}},
  doi = {10.1051/eas/1465004},
  abstract = {Among the various methods used to age-date stars, methods based on
stellar model predictions are widely used, for nearly all kind of stars
in large ranges of masses, chemical compositions and evolutionary
stages. The precision and accuracy on the age determination depend on
both the precision and number of observational constraints, and on our
ability to correctly describe the stellar interior and evolution. The
imperfect input physics of stellar models as well as the uncertainties
on the initial chemical composition of stars are responsible for
uncertainties in the age determination. We present an overview of the
calculation of stellar models and discuss the impact on age of their
numerous inputs.},
  file = {/Users/Oliver/Zotero/storage/IMKUW24C/Lebreton et al. - 2014 - How accurate are stellar ages based on stellar mod.pdf}
}

@article{lebreton+2014a,
  title = {How Accurate Are Stellar Ages Based on Stellar Models?. {{II}}. {{The}} Impact of Asteroseismology},
  shorttitle = {How Accurate Are Stellar Ages Based on Stellar Models?},
  author = {Lebreton, Y. and Goupil, M. J. and Montalb{\'a}n, J.},
  year = {2014},
  month = nov,
  volume = {65},
  pages = {177--223},
  address = {{eprint: arXiv:1410.5337}},
  doi = {10.1051/eas/1465005},
  abstract = {Accurate and precise stellar ages are best determined for stars which
are strongly observationally constrained, that is which are
intrinsically oscillating. We review here the seismic diagnostics which
are sensitive to stellar ages and provide some illustrating examples of
seismically age-dated stars.},
  file = {/Users/Oliver/Zotero/storage/LZW48FD6/Lebreton et al. - 2014 - How accurate are stellar ages based on stellar mod.pdf}
}

@article{ledoux1951,
  title = {The {{Nonradial Oscillations}} of {{Gaseous Stars}} and the {{Problem}} of {{Beta Canis Majoris}}.},
  author = {Ledoux, P.},
  year = {1951},
  month = nov,
  volume = {114},
  pages = {373},
  issn = {0004-637X, 1538-4357},
  doi = {10.1086/145477},
  abstract = {The general characteristics of the nonradial oscillations of a rotating star are summarized and compared with the observations of \ss{} Canis Majoris. It is shown that the existence of two periods very close to each other as well as a phase shift of a quarter-period between the broadening of the lines and the corresponding radial velocity can be accounted for if the oscillation corresponds to a spherical harmonic of degree 2 in a rotating star. However, for free oscillations, the sign of the phase shift is opposite to the one observed when the periods are in the correct ratio, and vice versa.},
  file = {/Users/Oliver/Zotero/storage/RKSHLKLL/Ledoux - 1951 - The Nonradial Oscillations of Gaseous Stars and th.pdf},
  journal = {The Astrophysical Journal},
  language = {en}
}

@article{leibacher+stein1971,
  title = {A {{New Description}} of the {{Solar Five}}-{{Minute Oscillation}}},
  author = {Leibacher, J. W. and Stein, R. F.},
  year = {1971},
  volume = {7},
  pages = {191--192},
  issn = {0004-6388},
  abstract = {Not Available},
  journal = {Astrophysical Letters},
  keywords = {GLOBAL MODES,JOHN LEIBACHER,THEORY}
}

@article{leighton+1962,
  title = {Velocity {{Fields}} in the {{Solar Atmosphere}}. {{I}}. {{Preliminary Report}}.},
  author = {Leighton, Robert B. and Noyes, Robert W. and Simon, George W.},
  year = {1962},
  month = mar,
  volume = {135},
  pages = {474},
  issn = {0004-637X},
  doi = {10.1086/147285},
  abstract = {Abstract image available at:
http://adsabs.harvard.edu/abs/1962ApJ...135..474L},
  file = {/Users/Oliver/Zotero/storage/B5H6A4CA/Leighton et al. - 1962 - Velocity Fields in the Solar Atmosphere. I. Prelim.pdf},
  journal = {The Astrophysical Journal}
}

@article{leiner+2019,
  title = {Blue {{Lurkers}}: {{Hidden Blue Stragglers}} on the {{M67 Main Sequence Identified}} from {{Their Kepler}}/{{K2 Rotation Periods}}},
  shorttitle = {Blue {{Lurkers}}},
  author = {Leiner, Emily and Mathieu, Robert D. and Vanderburg, Andrew and Gosnell, Natalie M. and Smith, Jeffrey C.},
  year = {2019},
  month = aug,
  volume = {881},
  pages = {47},
  issn = {0004-637X},
  doi = {10.3847/1538-4357/ab2bf8},
  abstract = {At an age of 4 Gyr, typical solar-type stars in M67 have rotation rates of 20-30 days. Using K2 Campaign 5 and 16 light curves and the spectral archive of the WIYN Open Cluster Study, we identify 11 3D kinematic members of M67 with anomalously fast rotation periods of 2-8 days, implying ages of less than 1 Gyr. We hypothesize that these anomalously fast rotators have been spun up by mass transfer, mergers, or stellar collisions during dynamical encounters within the 1 Gyr and thus represent lower-luminosity counterparts to the blue straggler stars. These 11 candidate post-interaction stellar systems have much in common with the blue stragglers, including a high binary fraction (73\%); a number of long-period, low-eccentricity binary systems; and in at least one case a UV excess consistent with the presence of a hot white dwarf companion. The identification of these 11 systems provides the first picture of the low-luminosity end of the blue straggler distribution, providing new constraints for detailed binary evolution models and cluster population studies. This result also clearly demonstrates the need to properly account for the impact of binaries on stellar evolution, as significant numbers of post-interaction binaries likely exist on cluster main sequences and in the field. These stars are not always easy to identify but make up{\~ }10\% or more of the spectroscopic binary population among the solar-type stars in M67.},
  file = {/Users/Oliver/Zotero/storage/C39XVRJN/Leiner et al. - 2019 - Blue Lurkers Hidden Blue Stragglers on the M67 Ma.pdf;/Users/Oliver/Zotero/storage/E9LRTYX7/abstract.html},
  journal = {The Astrophysical Journal},
  language = {en},
  number = {1}
}

@article{leistedt+2018,
  title = {Hierarchical Modeling and Statistical Calibration for Photometric Redshifts},
  author = {Leistedt, Boris and Hogg, David W. and Wechsler, Risa H. and DeRose, Joe},
  year = {2018},
  month = jul,
  pages = {arXiv:1807.01391},
  abstract = {The cosmological exploitation of modern photometric galaxy surveys requires both accurate (unbiased) and precise (narrow) redshift probability distributions derived from broadband photometry. Existing methodologies do not meet those requirements. Standard template fitting delivers interpretable models and errors, but lacks flexibility to learn inaccuracies in the observed photometry or the spectral templates. Machine learning addresses those issues, but requires representative training data, and the resulting models and uncertainties cannot be interpreted in the context of a physical model or outside of the training data. We present a hierarchical modeling approach simultaneously addressing the issues of flexibility, interpretability, and generalization. It combines template fitting with flexible (machine learning-like) models to correct the spectral templates, model their redshift distributions, and recalibrate the photometric observations. By optimizing the full posterior distribution of the model and solving for its (thousands of) parameters, one can perform a global statistical calibration of the data and the SED model. We apply this approach to the public Dark Energy Survey Science Verification data, and show that it provides more accurate and compact redshift posterior distributions than existing methods, as well as insights into residual photometric and SED systematics. The model is causal, makes predictions for future data (e.g., additional photometric bandpasses), and its internal parameters and components are interpretable. This approach does not formally require the training data to be complete or representative; in principle it can even work in regimes in which few or no spectroscopic redshifts are available.},
  file = {/Users/Oliver/Zotero/storage/76VSIK5G/Leistedt et al. - 2018 - Hierarchical modeling and statistical calibration .pdf;/Users/Oliver/Zotero/storage/HW8WMWNP/ui.adsabs.harvard.edu.html},
  journal = {ArXiv e-prints},
  language = {en}
}

@article{leistedt+hogg2017,
  title = {Hierarchical {{Probabilistic Inference}} of the {{Color}}-{{Magnitude Diagram}} and {{Shrinkage}} of {{Stellar Distance Uncertainties}}},
  author = {Leistedt, Boris and Hogg, David W.},
  year = {2017},
  month = dec,
  volume = {154},
  pages = {222},
  doi = {10.3847/1538-3881/aa91d5},
  abstract = {We present a hierarchical probabilistic model for improving geometric stellar distance estimates using color-magnitude information. This is achieved with a data-driven model of the color-magnitude diagram, not relying on stellar models but instead on the relative abundances of stars in color-magnitude cells, which are inferred from very noisy magnitudes and parallaxes. While the resulting noise-deconvolved color-magnitude diagram can be useful for a range of applications, we focus on deriving improved stellar distance estimates relying on both parallax and photometric information. We demonstrate the efficiency of this approach on the 1.4 million stars of the Gaia TGAS sample that also have AAVSO Photometric All Sky Survey magnitudes. Our hierarchical model has 4 million parameters in total, most of which are marginalized out numerically or analytically. We find that distance estimates are significantly improved for the noisiest parallaxes and densest regions of the color-magnitude diagram. In particular, the average distance signal-to-noise ratio (S/N) and uncertainty improve by 19\% and 36\%, respectively, with 8\% of the objects improving in S/N by a factor greater than 2. This computationally efficient approach fully accounts for both parallax and photometric noise and is a first step toward a full hierarchical probabilistic model of the Gaia data.},
  file = {/Users/Oliver/Zotero/storage/NNEVVKV7/Leistedt and Hogg - 2017 - Hierarchical Probabilistic Inference of the Color-.pdf;/Users/Oliver/Zotero/storage/TLLKQMS5/ui.adsabs.harvard.edu.html},
  journal = {The Astronomical Journal},
  language = {en},
  number = {6}
}

@article{lightkurvecollaboration+2018,
  title = {Lightkurve: {{Kepler}} and {{TESS}} Time Series Analysis in {{Python}}},
  shorttitle = {Lightkurve},
  author = {{Lightkurve Collaboration} and Cardoso, Jos{\'e} Vin{\'i}cius de Miranda and Hedges, Christina and {Gully-Santiago}, Michael and Saunders, Nicholas and Cody, Ann Marie and Barclay, Thomas and Hall, Oliver and Sagear, Sheila and Turtelboom, Emma and Zhang, Johnny and Tzanidakis, Andy and Mighell, Ken and Coughlin, Jeff and Bell, Keaton and {Berta-Thompson}, Zach and Williams, Peter and Dotson, Jessie and Barentsen, Geert},
  year = {2018},
  month = dec,
  pages = {ascl:1812.013},
  abstract = {Lightkurve analyzes astronomical flux time series data, in particular the pixels and light curves obtained by NASA's Kepler, K2, and
TESS exoplanet missions. This community-developed Python package is designed to be user friendly to lower the barrier for students,
astronomers, and citizen scientists interested in analyzing data from these missions. Lightkurve provides easy tools to download, inspect, and analyze time series data and its documentation is supported by a large syllabus of tutorials.},
  journal = {Astrophysics Source Code Library},
  keywords = {NASA,Software}
}

@article{lindegren+2012,
  title = {The Astrometric Core Solution for the {{Gaia}} Mission. {{Overview}} of Models, Algorithms, and Software Implementation},
  author = {Lindegren, L. and Lammers, U. and Hobbs, D. and O'Mullane, W. and Bastian, U. and Hern{\'a}ndez, J.},
  year = {2012},
  month = feb,
  volume = {538},
  pages = {A78},
  doi = {10.1051/0004-6361/201117905},
  abstract = {Context. The Gaia satellite will observe about one billion stars and other point-like sources. The astrometric core solution will determine the astrometric parameters (position, parallax, and proper motion) for a subset of these sources, using a global solution approach which must also include a large number of parameters for the satellite attitude and optical instrument. The accurate and efficient implementation of this solution is an extremely demanding task, but crucial for the outcome of the mission. \\
 Aims: We aim to provide a comprehensive overview of the mathematical and physical models applicable to this solution, as well as its numerical and algorithmic framework. \\
 Methods: The astrometric core solution is a simultaneous least-squares estimation of about half a billion parameters, including the astrometric parameters for some 100 million well-behaved so-called primary sources. The global nature of the solution requires an iterative approach, which can be broken down into a small number of distinct processing blocks (source, attitude, calibration and global updating) and auxiliary processes (including the frame rotator and selection of primary sources). We describe each of these processes in some detail, formulate the underlying models, from which the observation equations are derived, and outline the adopted numerical solution methods with due consideration of robustness and the structure of the resulting system of equations. Appendices provide brief introductions to some important mathematical tools (quaternions and B-splines for the attitude representation, and a modified Cholesky algorithm for positive semidefinite problems) and discuss some complications expected in the real mission data. \\
 Results: A complete software system called AGIS (Astrometric Global Iterative Solution) is being built according to the methods described in the paper. Based on simulated data for 2 million primary sources we present some initial results, demonstrating the basic mathematical and numerical validity of the approach and, by a reasonable extrapolation, its practical feasibility in terms of data management and computations for the real mission.},
  file = {/Users/Oliver/Zotero/storage/8C4B45SF/Lindegren et al. - 2012 - The astrometric core solution for the Gaia mission.pdf;/Users/Oliver/Zotero/storage/K94IJX6G/ui.adsabs.harvard.edu.html},
  journal = {Astronomy and Astrophysics},
  language = {en}
}

@article{lindegren+2016,
  title = {Gaia {{Data Release}} 1. {{Astrometry}}: One Billion Positions, Two Million Proper Motions and Parallaxes},
  shorttitle = {Gaia {{Data Release}} 1. {{Astrometry}}},
  author = {Lindegren, L. and Lammers, U. and Bastian, U. and Hern{\'a}ndez, J. and Klioner, S. and Hobbs, D. and Bombrun, A. and Michalik, D. and {Ramos-Lerate}, M. and Butkevich, A. and Comoretto, G. and Joliet, E. and Holl, B. and Hutton, A. and Parsons, P. and Steidelm{\"u}ller, H. and Abbas, U. and Altmann, M. and Andrei, A. and Anton, S. and Bach, N. and Barache, C. and Becciani, U. and Berthier, J. and Bianchi, L. and Biermann, M. and Bouquillon, S. and Bourda, G. and Br{\"u}semeister, T. and Bucciarelli, B. and Busonero, D. and Carlucci, T. and Casta{\~n}eda, J. and Charlot, P. and Clotet, M. and Crosta, M. and Davidson, M. and {de Felice}, F. and Drimmel, R. and Fabricius, C. and Fienga, A. and Figueras, F. and Fraile, E. and Gai, M. and Garralda, N. and Geyer, R. and {Gonz{\'a}lez-Vidal}, J. J. and Guerra, R. and Hambly, N. C. and Hauser, M. and Jordan, S. and Lattanzi, M. G. and Lenhardt, H. and Liao, S. and L{\"o}ffler, W. and McMillan, P. J. and Mignard, F. and Mora, A. and Morbidelli, R. and Portell, J. and Riva, A. and Sarasso, M. and Serraller, I. and Siddiqui, H. and Smart, R. and Spagna, A. and Stampa, U. and Steele, I. and Taris, F. and Torra, J. and {van Reeven}, W. and Vecchiato, A. and Zschocke, S. and {de Bruijne}, J. and Gracia, G. and Raison, F. and Lister, T. and Marchant, J. and Messineo, R. and Soffel, M. and Osorio, J. and {de Torres}, A. and O'Mullane, W.},
  year = {2016},
  month = nov,
  volume = {595},
  pages = {A4},
  doi = {10.1051/0004-6361/201628714},
  abstract = {Context. Gaia Data Release 1 (DR1) contains astrometric results for more than 1 billion stars brighter than magnitude 20.7 based on observations collected by the Gaia satellite during the first 14 months of its operational phase. \\
 Aims: We give a brief overview of the astrometric content of the data release and of the model assumptions, data processing, and validation of the results. \\
 Methods: For stars in common with the Hipparcos and Tycho-2 catalogues, complete astrometric single-star solutions are obtained by incorporating positional information from the earlier catalogues. For other stars only their positions are obtained, essentially by neglecting their proper motions and parallaxes. The results are validated by an analysis of the residuals, through special validation runs, and by comparison with external data. \\
 Results: For about two million of the brighter stars (down to magnitude 11.5) we obtain positions, parallaxes, and proper motions to Hipparcos-type precision or better. For these stars, systematic errors depending for example on position and colour are at a level of {$\pm$} 0.3 milliarcsecond (mas). For the remaining stars we obtain positions at epoch J2015.0 accurate to 10 mas. Positions and proper motions are given in a reference frame that is aligned with the International Celestial Reference Frame (ICRF) to better than 0.1 mas at epoch J2015.0, and non-rotating with respect to ICRF to within 0.03 mas yr\textsuperscript{-1}. The Hipparcos reference frame is found to rotate with respect to the Gaia DR1 frame at a rate of 0.24 mas yr\textsuperscript{-1}. \\
 Conclusions: Based on less than a quarter of the nominal mission length and on very provisional and incomplete calibrations, the quality and completeness of the astrometric data in Gaia DR1 are far from what is expected for the final mission products. The present results nevertheless represent a huge improvement in the available fundamental stellar data and practical definition of the optical reference frame.},
  file = {/Users/Oliver/Zotero/storage/LJKYFN95/Lindegren et al. - 2016 - Gaia Data Release 1. Astrometry one billion posit.pdf;/Users/Oliver/Zotero/storage/TZS9VZC3/ui.adsabs.harvard.edu.html},
  journal = {Astronomy and Astrophysics},
  language = {en}
}

@article{lindegren+2018,
  title = {Gaia {{Data Release}} 2: {{The}} Astrometric Solution},
  shorttitle = {Gaia {{Data Release}} 2},
  author = {Lindegren, L. and Hernandez, J. and Bombrun, A. and Klioner, S. and Bastian, U. and {Ramos-Lerate}, M. and {de Torres}, A. and Steidelmuller, H. and Stephenson, C. and Hobbs, D. and Lammers, U. and Biermann, M. and Geyer, R. and Hilger, T. and Michalik, D. and Stampa, U. and McMillan, P. J. and Castaneda, J. and Clotet, M. and Comoretto, G. and Davidson, M. and Fabricius, C. and Gracia, G. and Hambly, N. C. and Hutton, A. and Mora, A. and Portell, J. and {van Leeuwen}, F. and Abbas, U. and Abreu, A. and Altmann, M. and Andrei, A. and Anglada, E. and {Balaguer-Nunez}, L. and Barache, C. and Becciani, U. and Bertone, S. and Bianchi, L. and Bouquillon, S. and Bourda, G. and Brusemeister, T. and Bucciarelli, B. and Busonero, D. and Buzzi, R. and Cancelliere, R. and Carlucci, T. and Charlot, P. and Cheek, N. and Crosta, M. and Crowley, C. and {de Bruijne}, J. and {de Felice}, F. and Drimmel, R. and Esquej, P. and Fienga, A. and Fraile, E. and Gai, M. and Garralda, N. and {Gonzalez-Vidal}, J. J. and Guerra, R. and Hauser, M. and Hofmann, W. and Holl, B. and Jordan, S. and Lattanzi, M. G. and Lenhardt, H. and Liao, S. and Licata, E. and Lister, T. and Loffler, W. and Marchant, J. and {Martin-Fleitas}, J.-M. and Messineo, R. and Mignard, F. and Morbidelli, R. and Poggio, E. and Riva, A. and Rowell, N. and Salguero, E. and Sarasso, M. and Sciacca, E. and Siddiqui, H. and Smart, R. L. and Spagna, A. and Steele, I. and Taris, F. and Torra, J. and {van Elteren}, A. and {van Reeven}, W. and Vecchiato, A.},
  year = {2018},
  month = apr,
  pages = {arXiv:1804.09366},
  abstract = {Gaia Data Release 2 (Gaia DR2) contains results for 1693 million sources in the magnitude range 3 to 21 based on observations collected by the European Space Agency Gaia satellite during the first 22 months of its operational phase. We describe the input data, models, and processing used for the astrometric content of Gaia DR2, and the validation of these results performed within the astrometry task. Some 320 billion centroid positions from the pre-processed astrometric CCD observations were used to estimate the five astrometric parameters (positions, parallaxes, and proper motions) for 1332 million sources, and approximate positions at the reference epoch J2015.5 for an additional 361 million mostly faint sources. Special validation solutions were used to characterise the random and systematic errors in parallax and proper motion. For the sources with five-parameter astrometric solutions, the median uncertainty in parallax and position at the reference epoch J2015.5 is about 0.04 mas for bright (G\<14 mag) sources, 0.1 mas at G=17 mag, and 0.7 mas at G=20 mag. In the proper motion components the corresponding uncertainties are 0.05, 0.2, and 1.2 mas/yr, respectively. The optical reference frame defined by Gaia DR2 is aligned with ICRS and is non-rotating with respect to the quasars to within 0.15 mas/yr. From the quasars and validation solutions we estimate that systematics in the parallaxes depending on position, magnitude, and colour are generally below 0.1 mas, but the parallaxes are on the whole too small by about 0.03 mas. Significant spatial correlations of up to 0.04 mas in parallax and 0.07 mas/yr in proper motion are seen on small (\<1 deg) and intermediate (20 deg) angular scales. Important statistics and information for the users of the Gaia DR2 astrometry are given in the appendices.},
  file = {/Users/Oliver/Zotero/storage/YWI6KCTD/Lindegren et al. - 2018 - Gaia Data Release 2 The astrometric solution.pdf;/Users/Oliver/Zotero/storage/NZEKDUT9/ui.adsabs.harvard.edu.html},
  journal = {ArXiv e-prints},
  language = {en}
}

@article{lomb1976,
  title = {Least-{{Squares Frequency Analysis}} of {{Unequally Spaced Data}}},
  author = {Lomb, N. R.},
  year = {1976},
  month = feb,
  volume = {39},
  pages = {447},
  doi = {10.1007/BF00648343},
  abstract = {The statistical properties of least-squares frequency analysis of unequally spaced data are examined. It is shown that, in the least-squares spectrum of gaussian noise, the reduction in the sum of squares at a particular frequency is aX \{\vphantom\}\textsubscript{2}/\textsuperscript{2}\vphantom\{\} variable. The reductions at different frequencies are not independent, as there is a correlation between the height of the spectrum at any two frequencies,f \textsubscript{1} andf \textsubscript{2}, which is equal to the mean height of the spectrum due to a sinusoidal signal of frequencyf \textsubscript{1}, at the frequencyf \textsubscript{2}. These correlations reduce the distortion in the spectrum of a signal affected by noise. Some numerical illustrations of the properties of least-squares frequency spectra are also given.},
  file = {/Users/Oliver/Zotero/storage/QFFFJVFC/abstract.html},
  journal = {Astrophysics and Space Science},
  language = {en}
}

@article{lopes+turck-chieze1994,
  title = {The Second Order Asymptotic Theory for the Solar and Stellar Low Degree Acoustic Mode Predictions},
  author = {Lopes, I. and {Turck-Chieze}, S.},
  year = {1994},
  month = oct,
  volume = {290},
  pages = {845--860},
  issn = {0004-6361},
  abstract = {We discuss the new asymptotic formulae, obtained by Tassoul and
Vorontsov without the Cowling approximation, for the acoustic modes of
low degree. We deduce second-order asymptotic expressions which recover
the absolute value of the solar calculated eigenfrequencies within
10{$\mu$}Hz for degrees lower than 12 and frequencies between
1mHz{$<$}={$\nu<$}=5mHz. This result is compared with the previous ones
obtained in a first or second-order asymptotic theories. The different
seismic parameters: \{DELTA\}{$\nu\_$}l,n\_ , {$\delta\_$}2nu\_l,n\_ and
{$\delta\nu\_$}l,n\_ , the phase shift {$\alpha$} and its derivative
{$\beta\_$}l,n\_ are also determined and the influence of the different
physical processes are emphasized.},
  file = {/Users/Oliver/Zotero/storage/4MUFLIKN/Lopes and Turck-Chieze - 1994 - The second order asymptotic theory for the solar a.pdf},
  journal = {Astronomy and Astrophysics},
  keywords = {STARS: OSCILLATIONS,SUN: OSCILLATIONS}
}

@article{lopes2016,
  title = {The {{Sun}} as a Probe of {{Fundamental Physics}} and {{Cosmology}}},
  author = {Lopes, Il{\'i}dio},
  year = {2016},
  month = jan,
  volume = {665},
  pages = {012079},
  issn = {1742-6588, 1742-6596},
  doi = {10.1088/1742-6596/665/1/012079},
  abstract = {The high quality data provided by helioseismology, solar neutrino flux measurements, spectral determination of solar abundances, nuclear reactions rates coefficients among other experimental data, leads to the highly accurate prediction of the internal structure of the present Sun - the standard solar model. In this talk, I have discussed how the standard solar model, the best representation of the real Sun, can be used to study the properties of dark matter, for which two complementary approaches have been developed: - to limit the number of theoretical candidates proposed as the dark matter particles, this analysis complements the experimental search of dark matter, and - as a template for the study of the impact of dark matter in the evolution of stars, which possibly occurs for stellar populations formed in regions of high density of dark matter, such as stars formed in the centre of galaxies and the first generations of stars.},
  archivePrefix = {arXiv},
  eprint = {1701.03926},
  eprinttype = {arxiv},
  file = {/Users/Oliver/Zotero/storage/UEBQ4UNV/Lopes - 2016 - The Sun as a probe of Fundamental Physics and Cosm.pdf;/Users/Oliver/Zotero/storage/ZCK9XTXF/1701.html},
  journal = {Journal of Physics: Conference Series},
  keywords = {Astrophysics - Cosmology and Nongalactic Astrophysics,Astrophysics - Solar and Stellar Astrophysics,Nuclear Experiment,Nuclear Theory}
}

@article{lorenzo-oliveira+2018,
  title = {The {{Solar Twin Planet Search}}. {{The}} Age-Chromospheric Activity Relation},
  author = {{Lorenzo-Oliveira}, Diego and Freitas, Fabr{\'i}cio C. and Mel{\'e}ndez, Jorge and Bedell, Megan and Ram{\'i}rez, Iv{\'a}n and Bean, Jacob L. and Asplund, Martin and Spina, Lorenzo and Dreizler, Stefan and {Alves-Brito}, Alan and Casagrande, Luca},
  year = {2018},
  month = nov,
  volume = {619},
  pages = {A73},
  doi = {10.1051/0004-6361/201629294},
  abstract = {Context. It is well known that the magnetic activity of solar-type stars decreases with age, but it is widely debated in the literature whether there is a smooth decline or if there is an early sharp drop until 1-2 Gyr that is followed by a relatively inactive constant phase. \\
 Aims: We revisited the activity-age relation using time-series observations of a large sample of solar twins whose precise isochronal ages and other important physical parameters have been determined. \\
 Methods: We measured the Ca II H and K activity indices using {$\approx$}9000 HARPS spectra of 82 solar twins. In addition, the average solar activity was calculated through asteroids and Moon reflection spectra using the same instrumentation. Thus, we transformed our activity indices into the S Mount Wilson scale (S\textsubscript{MW}), recalibrated the Mount Wilson absolute flux and photospheric correction equations as a function of T\textsubscript{eff}, and then computed an improved bolometric flux normalized activity index log R'\textsubscript{HK} (T\textsubscript{eff}) for the entire sample. \\
 Results: New relations between activity and the age of solar twins were derived by assessing the chromospheric age-dating limits using log R'\textsubscript{HK} (T\textsubscript{eff}). We measured an average solar activity of S\textsubscript{MW} = 0.1712 {$\pm$} 0.0017 during solar magnetic cycles 23-24 covered by HARPS observations, and we also inferred an average of S\textsubscript{MW} = 0.1694 {$\pm$} 0.0025 for cycles 10-24, anchored on a sunspot number correlation of S index versus. We also found a simple relation between the average and the dispersion of the activity levels of solar twins. This enabled us to predict the stellar variability effects on the age-activity diagram, and consequently, to estimate the chromospheric age uncertainties that are due to the same phenomena. The age-activity relation is still statistically significant up to ages around 6-7 Gyr, in agreement with previous works using open clusters and field stars with precise ages. \\
 Conclusions: Our research confirms that Ca II H \& K lines remain a useful chromospheric evolution tracer until stars reach ages of at least 6-7 Gyr. We found evidence that for the most homogenous set of old stars, the chromospheric activity indices seem to continue to decrease after the solar age toward the end of the main sequence. Our results indicate that a significant part of the scatter observed in the age-activity relation of solar twins can be attributed to stellar cycle modulations effects. The Sun seems to have a normal activity level and variability for its age. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programs 188.C-0265, 183.D-0729, 292.C-5004, 097.C-0571, 092.C-0721, 093.C-0409, 072.C-0488, 183.C-0972, 091.C-0936, 192.C-0852, 196.C-1006, 076.C-0155, 096.C-0499, 185.D-0056, 192.C-0224, 075.C-0332, 090.C-0421, 091.C-0034, 077.C-0364, 089.C-0415, 60.A-9036, 092.C-0832, 295.C-5035, 295.C-5031, 60.A-9700, 289.D-5015, 096.C-0210, 086.C-0284, 088.C-0323, 0100.D-0444, and 099.C-0491.Tables 1 and 2 are only available at the CDS via anonymous ftp to \href{http://cdsarc.u-strasbg.fr}{http://cdsarc.u-strasbg.fr} (ftp://130.79.128.5) or via \href{http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/619/A73}{http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/619/A73}},
  file = {/Users/Oliver/Zotero/storage/349BAQT9/Lorenzo-Oliveira et al. - 2018 - The Solar Twin Planet Search. The age-chromospheri.pdf;/Users/Oliver/Zotero/storage/PKVWI328/abstract.html},
  journal = {Astronomy and Astrophysics},
  language = {en}
}

@article{lorenzo-oliveira+2019,
  title = {Constraining the Evolution of Stellar Rotation Using Solar Twins},
  author = {{Lorenzo-Oliveira}, Diego and Mel{\'e}ndez, Jorge and Yana Galarza, Jhon and Ponte, Geisa and {dos Santos}, Leonardo A. and Spina, Lorenzo and Bedell, Megan and Ram{\'i}rez, Iv{\'a}n and Bean, Jacob L. and Asplund, Martin},
  year = {2019},
  month = may,
  volume = {485},
  pages = {L68},
  doi = {10.1093/mnrasl/slz034},
  abstract = {The stellar rotation versus age relation is commonly considered a useful tool to derive reliable ages for Sun-like stars. However, in the light of Kepler data, the presence of apparently old and fast rotators that do not obey the usual gyrochronology relations led to the hypothesis of weakened magnetic breaking in some stars. In this letter, we constrain the solar rotation evolutionary track using solar twins. Predicted rotational periods as a function of mass, age, [Fe/H], and given critical Rossby number (Ro\textsubscript{crit}) were estimated for the entire rotational sample. Our analysis favours the smooth rotational evolution scenario and suggests that if the magnetic weakened breaking scenario takes place at all, it should arise after Ro\textsubscript{crit} {$\greaterequivlnt$} 2.29 or ages {$\greaterequivlnt$}5.3 Gyr (at 95 per cent confidence level).},
  file = {/Users/Oliver/Zotero/storage/JFJC5F6V/Lorenzo-Oliveira et al. - 2019 - Constraining the evolution of stellar rotation usi.pdf;/Users/Oliver/Zotero/storage/65RP32VR/abstract.html},
  journal = {Monthly Notices of the Royal Astronomical Society},
  language = {en},
  number = {1}
}

@article{lorenzo-oliveira+2020,
  title = {The Ancient Main-Sequence Solar Proxy {{HIP}} 102152 Unveils the Activity and Rotational Fate of Our {{Sun}}},
  author = {{Lorenzo-Oliveira}, Diego and Mel{\'e}ndez, Jorge and Ponte, Geisa and Galarza, Jhon Yana},
  year = {2020},
  month = mar,
  volume = {2003},
  pages = {arXiv:2003.13871},
  abstract = {We present a detailed analysis of the possible future Sun's rotational
evolution scenario based on the 8 Gyr-old solar twin HIP 102152. Using
HARPS high-cadence observations (and TESS light curves), we analyzed the
modulation of a variety of activity proxies (Ca II, HI Balmer, and Na I
lines), finding a strong rotational signal of 35.7 \$\textbackslash pm\$ 1.4 days (\$\textbackslash log
B\_\{\textbackslash rm factor\}\textbackslash sim70\$, in the case of Ca II K line). This value matches
with the theoretical expectations regarding the smooth rotational
evolution of the Sun towards the end of the main-sequence, validating
the use of gyrochronology after solar age.},
  file = {/Users/Oliver/Zotero/storage/H84QDWGX/Lorenzo-Oliveira et al. - 2020 - The ancient main-sequence solar proxy HIP 102152 u.pdf},
  journal = {arXiv e-prints},
  keywords = {Astrophysics - Earth and Planetary Astrophysics,Astrophysics - Solar and Stellar Astrophysics}
}

@article{luger+2016,
  title = {{{EVEREST}}: {{Pixel Level Decorrelation}} of {{K2 Light}} Curves},
  shorttitle = {{{EVEREST}}},
  author = {Luger, Rodrigo and Agol, Eric and Kruse, Ethan and Barnes, Rory and Becker, Andrew and {Foreman-Mackey}, Daniel and Deming, Drake},
  year = {2016},
  month = oct,
  volume = {152},
  pages = {100},
  issn = {1538-3881},
  doi = {10.3847/0004-6256/152/4/100},
  abstract = {We present EVEREST, an open-source pipeline for removing instrumental noise from K2 light curves. EVEREST employs a variant of pixel level decorrelation (PLD) to remove systematics introduced by the spacecraft's pointing error and a Gaussian process (GP) to capture astrophysical variability. We apply EVEREST to all K2 targets in campaigns 0-7, yielding light curves with precision comparable to that of the original Kepler mission for stars brighter than \$K\_p \textbackslash approx 13\$, and within a factor of two of the Kepler precision for fainter targets. We perform cross-validation and transit injection and recovery tests to validate the pipeline, and compare our light curves to the other de-trended light curves available for download at the MAST High Level Science Products archive. We find that EVEREST achieves the highest average precision of any of these pipelines for unsaturated K2 stars. The improved precision of these light curves will aid in exoplanet detection and characterization, investigations of stellar variability, asteroseismology, and other photometric studies. The EVEREST pipeline can also easily be applied to future surveys, such as the TESS mission, to correct for instrumental systematics and enable the detection of low signal-to-noise transiting exoplanets. The EVEREST light curves and the source code used to generate them are freely available online.},
  archivePrefix = {arXiv},
  eprint = {1607.00524},
  eprinttype = {arxiv},
  file = {/Users/Oliver/Zotero/storage/JSQ4AHUM/Luger et al. - 2016 - EVEREST Pixel Level Decorrelation of K2 Light cur.pdf;/Users/Oliver/Zotero/storage/E635HGXK/1607.html},
  journal = {The Astronomical Journal},
  keywords = {C3},
  number = {4}
}

@article{luger+2017,
  title = {An Update to the {{EVEREST K2}} Pipeline: {{Short}} Cadence, Saturated Stars, and {{Kepler}}-like Photometry down to {{Kp}} = 15},
  shorttitle = {An Update to the {{EVEREST K2}} Pipeline},
  author = {Luger, Rodrigo and Kruse, Ethan and {Foreman-Mackey}, Daniel and Agol, Eric and Saunders, Nicholas},
  year = {2017},
  month = feb,
  abstract = {We present an update to the EVEREST K2 pipeline that addresses various limitations in the previous version and improves the photometric precision of the de-trended light curves. We develop a fast regularization scheme for third order pixel level decorrelation (PLD) and adapt the algorithm to include the PLD vectors of neighboring stars to enhance the predictive power of the model and minimize overfitting, particularly for faint stars. We also modify PLD to work for saturated stars and improve its performance on extremely variable stars. On average, EVEREST 2.0 light curves have 10-20\% higher photometric precision than those in the previous version, yielding the highest precision light curves at all Kp magnitudes of any publicly available K2 catalog. For most K2 campaigns, we recover the original Kepler precision to at least Kp = 14, and to at least Kp = 15 for campaigns 1, 5, and 6. We also de-trend all short cadence targets observed by K2, obtaining even higher photometric precision for these stars. All light curves for campaigns 0-8 are available online in the EVEREST catalog, which will be continuously updated with future campaigns. EVEREST 2.0 is open source and is coded in a general framework that can be applied to other photometric surveys, including Kepler and the upcoming TESS mission.},
  archivePrefix = {arXiv},
  eprint = {1702.05488},
  eprinttype = {arxiv},
  file = {/Users/Oliver/Zotero/storage/P2SR3A43/Luger et al. - 2017 - An update to the EVEREST K2 pipeline Short cadenc.pdf;/Users/Oliver/Zotero/storage/6IHIRKEA/1702.html},
  journal = {arXiv:1702.05488 [astro-ph]},
  keywords = {Astrophysics - Earth and Planetary Astrophysics,Astrophysics - Instrumentation and Methods for Astrophysics},
  primaryClass = {astro-ph}
}

@article{luger+2017a,
  title = {A Terrestrial-Sized Exoplanet at the Snow Line of {{TRAPPIST}}-1},
  author = {Luger, Rodrigo and Sestovic, Marko and Kruse, Ethan and Grimm, Simon L. and Demory, Brice-Olivier and Agol, Eric and Bolmont, Emeline and Fabrycky, Daniel and Fernandes, Catarina S. and Van Grootel, Val{\'e}rie and Burgasser, Adam and Gillon, Micha{\"e}l and Ingalls, James G. and Jehin, Emmanu{\"e}l and Raymond, Sean N. and Selsis, Franck and Triaud, Amaury H. M. J. and Barclay, Thomas and Barentsen, Geert and Delrez, Laetitia and {de Wit}, Julien and {Foreman-Mackey}, Daniel and Holdsworth, Daniel L. and Leconte, J{\'e}r{\'e}my and Lederer, Susan and Turbet, Martin and Almleaky, Yaseen and Benkhaldoun, Zouhair and Magain, Pierre and Morris, Brett and Heng, Kevin and Queloz, Didier},
  year = {2017},
  month = mar,
  abstract = {The TRAPPIST-1 system is the first transiting planet system found orbiting an ultra-cool dwarf star. At least seven planets similar to Earth in radius and in mass were previously found to transit this host star. Subsequently, TRAPPIST-1 was observed as part of the K2 mission and, with these new data, we report the measurement of an 18.764 d orbital period for the outermost planet, TRAPPIST-1h, which was unconstrained until now. This value matches our theoretical expectations based on Laplace relations and places TRAPPIST-1h as the seventh member of a complex chain, with three-body resonances linking every member. We find that TRAPPIST-1h has a radius of 0.715 Earth radii and an equilibrium temperature of 169 K, placing it at the snow line. We have also measured the rotational period of the star at 3.3 d and detected a number of flares consistent with an active, middle-aged, late M dwarf.},
  archivePrefix = {arXiv},
  eprint = {1703.04166},
  eprinttype = {arxiv},
  file = {/Users/Oliver/Zotero/storage/A895DACX/Luger et al. - 2017 - A terrestrial-sized exoplanet at the snow line of .pdf;/Users/Oliver/Zotero/storage/GF8QNMSC/1703.html},
  journal = {arXiv:1703.04166 [astro-ph]},
  keywords = {Astrophysics - Earth and Planetary Astrophysics,Astrophysics - Instrumentation and Methods for Astrophysics,Astrophysics - Solar and Stellar Astrophysics},
  primaryClass = {astro-ph}
}

@article{lund+2014,
  title = {Differential Rotation in Main-Sequence Solar-like Stars: {{Qualitative}} Inference from Asteroseismic Data},
  shorttitle = {Differential Rotation in Main-Sequence Solar-like Stars},
  author = {Lund, Mikkel N. and Miesch, Mark S. and {Christensen-Dalsgaard}, J{\o}rgen},
  year = {2014},
  month = jul,
  volume = {790},
  pages = {121},
  issn = {0004-637X, 1538-4357},
  doi = {10.1088/0004-637X/790/2/121},
  abstract = {Understanding differential rotation of Sun-like stars is of great importance for insight into the angular momentum transport in these stars. One means of gaining such information is that of asteroseismology. By a forward modeling approach we analyze in a qualitative manner the impact of different differential rotation profiles on the splittings of p-mode oscillation frequencies. The optimum modes for inference on differential rotation are identified along with the best value of the stellar inclination angle. We find that in general it is not likely that asteroseismology can be used to make an unambiguous distinction between a rotation profile such as, e.g., a conical Sun-like profile and a cylindrical profile. In addition, it seems unlikely that asteroseismology of Sun-like stars will result in inferences on the radial profile of the differential rotation, such as can be done for, e.g., red giants. At best one could possibly obtain the sign of the radial differential rotation gradient. Measurements of the extent of the latitudinal differential from frequency splitting are, however, more promising. One very interesting aspect that could likely be tested from frequency splittings is whether the differential rotation is solar-like or anti-solar-like in nature, in the sense that a solar-like profile has an equator rotating faster than the poles.},
  archivePrefix = {arXiv},
  eprint = {1406.7873},
  eprinttype = {arxiv},
  file = {/Users/Oliver/Zotero/storage/MYVAAF3K/Lund et al. - 2014 - Differential rotation in main-sequence solar-like .pdf;/Users/Oliver/Zotero/storage/SK5GC57B/1406.html},
  journal = {The Astrophysical Journal},
  keywords = {Astrophysics - Solar and Stellar Astrophysics},
  number = {2}
}

@article{lund+2015,
  title = {{{K2P2}}\textemdash{} {{A Photometry Pipeline}} for the {{K2 Mission}}},
  author = {Lund, Mikkel N. and Handberg, Rasmus and Davies, Guy R. and Chaplin, William J. and Jones, Caitlin D.},
  year = {2015},
  month = jun,
  volume = {806},
  pages = {30},
  issn = {0004-637X},
  doi = {10.1088/0004-637X/806/1/30},
  abstract = {With the loss of a second reaction wheel, resulting in the inability to point continuously and stably at the same field of view, the NASA Kepler satellite recently entered a new mode of observation known as the K2 mission. The data from this redesigned mission present a specific challenge; the targets systematically drift in position on an {$\sim$}6 hr timescale, inducing a significant instrumental signal in the photometric time series\textemdash this greatly impacts the ability to detect planetary signals and perform asteroseismic analysis. Here we detail our version of a reduction pipeline for K2 target pixel data, which automatically defines masks for all targets in a given frame; extracts the
target's flux and position time series; corrects the time series based on the apparent movement on the CCD (either in 1D or 2D), combined with the correction of instrumental and/or planetary signals via the Kepler Asteroseismic Science Operations Center (KASOC) filter, thus rendering the time series ready for asteroseismic analysis; computes power spectra for all targets and identifies potential contaminations between targets. From a test of our pipeline on a sample of targets from the K2 campaign 0, the recovery of data for multiple targets increases the amount of potential light curves by a factor of {$\geq$}slant 10. Our pipeline could be applied to the upcoming TESS and PLATO 2.0 missions.},
  file = {/Users/Oliver/Zotero/storage/FCI85URF/Lund et al. - 2015 - K2P2— A Photometry Pipeline for the K2 Mission.pdf},
  journal = {The Astrophysical Journal},
  keywords = {C3,Notes}
}

@article{lund+2016,
  title = {Asteroseismology of the {{Hyades}} with {{K2}}: First Detection of Main-Sequence Solar-like Oscillations in an Open Cluster},
  shorttitle = {Asteroseismology of the {{Hyades}} with {{K2}}},
  author = {Lund, Mikkel N. and Basu, Sarbani and Aguirre, V{\'i}ctor Silva and Chaplin, William J. and Serenelli, Aldo M. and Garc{\'i}a, Rafael A. and Latham, David W. and Casagrande, Luca and Bieryla, Allyson and Davies, Guy R. and Viani, Lucas S. and Buchhave, Lars A. and Miglio, Andrea and Soderblom, David R. and Valenti, Jeff A. and Stefanik, Robert P. and Handberg, Rasmus},
  year = {2016},
  month = dec,
  volume = {463},
  pages = {2600--2611},
  issn = {0035-8711, 1365-2966},
  doi = {10.1093/mnras/stw2160},
  abstract = {The Hyades open cluster was targeted during Campaign 4 (C4) of the NASA K2 mission, and short-cadence data were collected on a number of cool main-sequence stars. Here, we report results on two F-type stars that show detectable oscillations of a quality that allows asteroseismic analyses to be performed. These are the first ever detections of solar-like oscillations in main-sequence stars in an open cluster.},
  archivePrefix = {arXiv},
  eprint = {1608.07290},
  eprinttype = {arxiv},
  file = {/Users/Oliver/Zotero/storage/44YTCKLQ/Lund et al. - 2016 - Asteroseismology of the Hyades with K2 first dete.pdf;/Users/Oliver/Zotero/storage/U4YIHKXT/1608.html},
  journal = {Monthly Notices of the Royal Astronomical Society},
  keywords = {Astrophysics - Astrophysics of Galaxies,Astrophysics - Solar and Stellar Astrophysics},
  number = {3}
}

@article{lund+2016a,
  title = {Data Preparation for Asteroseismology with {{TESS}}},
  author = {Lund, Mikkel N. and Handberg, Rasmus and Kjeldsen, Hans and Chaplin, William J. and {Christensen-Dalsgaard}, J{\o}rgen},
  year = {2016},
  month = oct,
  abstract = {The Transiting Exoplanet Survey Satellite (TESS) is a NASA Astrophysics Explorer mission. Following its scheduled launch in 2017, TESS will focus on detecting exoplanets around the nearest and brightest stars in the sky, for which detailed follow-up observations are possible. TESS will, as the NASA Kepler mission, include a asteroseismic program that will be organized within the TESS Asteroseismic Science Consortium (TASC), building on the success of the Kepler Asteroseismic Science Consortium (KASC). Within TASC data for asteroseismic analysis will be prepared by the TASC Working Group 0 (WG-0), who will facilitate data to the community via the TESS Asteroseismic Science Operations Center (TASOC), again building on the success of the corresponding KASOC platform for Kepler. Here, we give an overview of the steps being taken within WG-0 to prepare for the upcoming TESS mission.},
  archivePrefix = {arXiv},
  eprint = {1610.02702},
  eprinttype = {arxiv},
  file = {/Users/Oliver/Zotero/storage/9AFB3N88/Lund et al. - 2016 - Data preparation for asteroseismology with TESS.pdf;/Users/Oliver/Zotero/storage/KIPHVJQ2/1610.html},
  journal = {arXiv:1610.02702 [astro-ph]},
  keywords = {C1,C3},
  primaryClass = {astro-ph}
}

@article{lund+2016b,
  title = {Asteroseismic Properties of Solar-Type Stars Observed with the {{NASA K2}} Mission: Results from {{Campaigns}} 1-3 and Prospects for Future Observations},
  shorttitle = {Asteroseismic Properties of Solar-Type Stars Observed with the {{NASA K2}} Mission},
  author = {Lund, Mikkel N. and Chaplin, William J. and Casagrande, Luca and Aguirre, V{\'i}ctor Silva and Basu, Sarbani and Bieryla, Allyson and {Christensen-Dalsgaard}, J{\o}rgen and Latham, David W. and White, Timothy R. and Davies, Guy R. and Huber, Daniel and Buchhave, Lars A. and Handberg, Rasmus},
  year = {2016},
  month = dec,
  volume = {128},
  pages = {124204},
  issn = {0004-6280, 1538-3873},
  doi = {10.1088/1538-3873/128/970/124204},
  abstract = {We present an asteroseismic analysis of 33 solar-type stars observed in short cadence during Campaigns (C) 1-3 of the NASA K2 mission. We were able to extract both average seismic parameters and individual mode frequencies for stars with dominant frequencies up to \textasciitilde 3300\{\textbackslash mu\}Hz, and we find that data for some targets are good enough to allow for a measurement of the rotational splitting. Modelling of the extracted parameters is performed by using grid-based methods using average parameters and individual frequencies together with spectroscopic parameters. For the target selection in C3, stars were chosen as in C1 and C2 to cover a wide range in parameter space to better understand the performance and noise characteristics. For C3 we still detected oscillations in 73\% of the observed stars that we proposed. Future K2 campaigns hold great promise for the study of nearby clusters and the chemical evolution and age-metallicity relation of nearby field stars in the solar neighbourhood. We expect oscillations to be detected in \textasciitilde 388 short-cadence targets if the K2 mission continues until C18, which will greatly complement the \textasciitilde 500 detections of solar-like oscillations made for short-cadence targets during the nominal Kepler mission. For \textasciitilde 30-40 of these, including several members of the Hyades open cluster, we furthermore expect that inference from interferometry should be possible.},
  archivePrefix = {arXiv},
  eprint = {1608.07292},
  eprinttype = {arxiv},
  file = {/Users/Oliver/Zotero/storage/IEH2JYAH/Lund et al. - 2016 - Asteroseismic properties of solar-type stars obser.pdf;/Users/Oliver/Zotero/storage/7JXCVSYW/1608.html},
  journal = {Publications of the Astronomical Society of the Pacific},
  keywords = {Astrophysics - Solar and Stellar Astrophysics},
  number = {970}
}

@article{lund+2017,
  title = {Standing on the {{Shoulders}} of {{Dwarfs}}: The {{Kepler Asteroseismic LEGACY Sample}}. {{I}}. {{Oscillation Mode Parameters}}},
  shorttitle = {Standing on the {{Shoulders}} of {{Dwarfs}}},
  author = {Lund, Mikkel N. and Silva Aguirre, V{\'i}ctor and Davies, Guy R. and Chaplin, William J. and {Christensen-Dalsgaard}, J{\o}rgen and Houdek, G{\"u}nter and White, Timothy R. and Bedding, Timothy R. and Ball, Warrick H. and Huber, Daniel and Antia, H. M. and Lebreton, Yveline and Latham, David W. and Handberg, Rasmus and Verma, Kuldeep and Basu, Sarbani and Casagrande, Luca and Justesen, Anders B. and Kjeldsen, Hans and Mosumgaard, Jakob R.},
  year = {2017},
  month = feb,
  volume = {835},
  pages = {172},
  doi = {10.3847/1538-4357/835/2/172},
  abstract = {The advent of space-based missions like Kepler has revolutionized the study of solar-type stars, particularly through the measurement and modeling of their resonant modes of oscillation. Here we analyze a sample of 66 Kepler main-sequence stars showing solar-like oscillations as part of the Kepler seismic LEGACY project. We use Kepler short-cadence data, of which each star has at least 12 months, to create frequency-power spectra optimized for asteroseismology. For each star, we identify its modes of oscillation and extract parameters such as frequency, amplitude, and line width using a Bayesian Markov chain Monte Carlo ``peak-bagging'' approach. We report the extracted mode parameters for all 66 stars, as well as derived quantities such as frequency difference ratios, the large and small separations \{\{{$\increment$} \}\}{$\nu$} and {$\delta$} \{{$\nu$} \}\textsubscript{02}; the behavior of line widths with frequency and line widths at \{{$\nu$} \}\textsubscript{\textbackslash max } with \{T\}\textsubscript{\{eff\vphantom\}}\vphantom\{\}, for which we derive parametrizations; and behavior of mode visibilities. These average properties can be applied in future peak-bagging exercises to better constrain the parameters of the stellar oscillation spectra. The frequencies and frequency ratios can tightly constrain the fundamental parameters of these solar-type stars, and mode line widths and amplitudes can test models of mode damping and excitation.},
  file = {/Users/Oliver/Zotero/storage/8HCEE3G5/Lund et al. - 2017 - Standing on the Shoulders of Dwarfs the Kepler As.pdf;/Users/Oliver/Zotero/storage/U6449TU3/ui.adsabs.harvard.edu.html},
  journal = {The Astrophysical Journal},
  keywords = {Seismic Age},
  language = {en},
  number = {2}
}

@article{lundkvist+2018,
  title = {Using Asteroseismology to Characterise Exoplanet Host Stars},
  author = {Lundkvist, Mia S. and Huber, Daniel and Aguirre, Victor Silva and Chaplin, William J.},
  year = {2018},
  month = apr,
  abstract = {The last decade has seen a revolution in the field of asteroseismology - the study of stellar pulsations. It has become a powerful method to precisely characterise exoplanet host stars, and as a consequence also the exoplanets themselves. This synergy between asteroseismology and exoplanet science has flourished in large part due to space missions such as \$\textbackslash textit\{Kepler\}\$, which have provided high-quality data that can be used for both types of studies. Perhaps the primary contribution from asteroseismology to the research on transiting exoplanets is the determination of very precise stellar radii that translate into precise planetary radii, but asteroseismology has also proven useful in constraining eccentricities of exoplanets as well as the dynamical architecture of planetary systems. In this contribution, we introduce some basic principles of asteroseismology and review current synergies between the two fields.},
  archivePrefix = {arXiv},
  eprint = {1804.02214},
  eprinttype = {arxiv},
  file = {/Users/Oliver/Zotero/storage/EXF2RXTG/Lundkvist et al. - 2018 - Using asteroseismology to characterise exoplanet h.pdf;/Users/Oliver/Zotero/storage/LS9S93EK/1804.html},
  journal = {arXiv:1804.02214 [astro-ph]},
  keywords = {Astrophysics - Earth and Planetary Astrophysics,Astrophysics - Solar and Stellar Astrophysics},
  primaryClass = {astro-ph}
}

@article{luri+2018,
  title = {Gaia {{Data Release}} 2: Using {{Gaia}} Parallaxes},
  shorttitle = {Gaia {{Data Release}} 2},
  author = {Luri, X. and Brown, A. G. A. and Sarro, L. M. and Arenou, F. and {Bailer-Jones}, C. a. L. and {Castro-Ginard}, A. and {de Bruijne}, J. and Prusti, T. and Babusiaux, C. and Delgado, H. E.},
  year = {2018},
  month = apr,
  pages = {arXiv:1804.09376},
  abstract = {The second Gaia data release (GDR2) provides precise five-parameter astrometric data (positions, proper motions and parallaxes) for an unprecedented amount of sources (more than \$1.3\$ billion, mostly stars). The use of this wealth of astrometric data comes with a specific challenge: how does one properly infer from these data the astrophysical parameters of interest? The main - but not only - focus of this paper is the issue of the estimation of distances from parallaxes, possibly combined with other information. We start with a critical review of the methods traditionally used to obtain distances from parallaxes and their shortcomings. Then we provide guidelines on how to use parallaxes more efficiently to estimate distances by using Bayesian methods. In particular also we show that negative parallaxes, or parallaxes with relatively larger uncertainties still contain valuable information. Finally, we provide examples that show more generally how to use astrometric data for parameter estimation, including the combination of proper motions and parallaxes and the handling of covariances in the uncertainties. The paper contains examples based on simulated Gaia data to illustrate the problems and the solutions proposed. Furthermore, the developments and methods proposed in the paper are linked to a set of tutorials included in the Gaia archive documentation that provide practical examples and a good starting point for the application of the recommendations to actual problems. In all cases the source code for the analysis methods is provided. Our main recommendation is to always treat the derivation of (astro-) physical parameters from astrometric data, in particular when parallaxes are involved, as an inference problem which should preferably be handled with a full Bayesian approach.},
  file = {/Users/Oliver/Zotero/storage/WHI75NYG/Luri et al. - 2018 - Gaia Data Release 2 using Gaia parallaxes.pdf;/Users/Oliver/Zotero/storage/RG5V49MT/ui.adsabs.harvard.edu.html},
  journal = {ArXiv e-prints},
  language = {en}
}

@article{maizapellaniz+weiler2018,
  title = {Reanalysis of the {{Gaia Data Release}} 2 Photometric Sensitivity Curves Using {{HST}}/{{STIS}} Spectrophotometry},
  author = {Ma{\'i}z Apell{\'a}niz, J. and Weiler, M.},
  year = {2018},
  month = nov,
  volume = {619},
  pages = {A180},
  doi = {10.1051/0004-6361/201834051},
  abstract = {Context. The second data release (DR2) from the European Space Agency mission Gaia took place on April 2018. DR2 included photometry for more than 1.3 \texttimes{} 10\textsuperscript{9} sources in the three bands G, G\textsubscript{BP}, and G\textsubscript{RP}. Even though the Gaia DR2 photometry is very precise, there are currently three alternative definitions of the sensitivity curves that show significative differences. \\
 Aims: The aim of this paper is to improve the quality of the input calibration data to produce new compatible definitions of the G, G\textsubscript{BP}, and G\textsubscript{RP} bands and to identify the reasons for the discrepancies between previous definitions. \\
 Methods: We have searched the Hubble Space Telescope (HST) archive for Space Telescope Imaging Spectrograph (STIS) spectra with G430L+G750L data obtained with wide apertures and combined them with the CALSPEC library to produce a high quality spectral energy distribution (SED) library of 122 stars with a broad range of colors, including three very red stars. This library defines new sensitivity curves for G, G\textsubscript{BP}, and G\textsubscript{RP} using a functional analytical formalism. \\
 Results: The new sensitivity curves are significantly better than the two previous attempts we use as a reference, REV (Evans et al. 2018, A\&A, 616, A4) and WEI (Weiler 2018, A\&A, 616, A17). For G we confirm the existence of a systematic bias in magnitude and correct a color term present in REV. For G\textsubscript{BP} we confirm the need to define two magnitude ranges with different sensitivity curves and measure the cut between them at G\textsubscript{phot} = 10.87 mag with a significant increase in precision. The new curves also fit the data better than either REV or WEI. For G\textsubscript{RP}, our new sensitivity curve fits the STIS spectra better and the differences with previous attempts reside in a systematic effect between ground-based and HST spectral libraries. Additional evidence from color-color diagrams indicate that the new sensitivity curve is more accurate. Nevertheless, there is still room for improvement in the accuracy of the sensitivity curves because of the current dearth of good-quality red calibrators: adding more to the sample should be a priority before Gaia data release 3 takes place. Table 2 is only available at the CDS via anonymous ftp to \href{http://cdsarc.u-strasbg.fr/}{http://cdsarc.u-strasbg.fr} (ftp://130.79.128.5) or via \href{http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/619/A180}{http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/619/A180}},
  file = {/Users/Oliver/Zotero/storage/9MSQATQY/Maíz Apellániz and Weiler - 2018 - Reanalysis of the Gaia Data Release 2 photometric .pdf;/Users/Oliver/Zotero/storage/WUSUU694/ui.adsabs.harvard.edu.html},
  journal = {Astronomy and Astrophysics},
  language = {en}
}

@article{majewski+2017,
  title = {The {{Apache Point Observatory Galactic Evolution Experiment}} ({{APOGEE}})},
  author = {Majewski, Steven R. and Schiavon, Ricardo P. and Frinchaboy, Peter M. and Allende Prieto, Carlos and Barkhouser, Robert and Bizyaev, Dmitry and Blank, Basil and Brunner, Sophia and Burton, Adam and Carrera, Ricardo and Chojnowski, S. Drew and Cunha, K{\'a}tia and Epstein, Courtney and Fitzgerald, Greg and Garc{\'i}a P{\'e}rez, Ana E. and Hearty, Fred R. and Henderson, Chuck and Holtzman, Jon A. and Johnson, Jennifer A. and Lam, Charles R. and Lawler, James E. and Maseman, Paul and M{\'e}sz{\'a}ros, Szabolcs and Nelson, Matthew and Nguyen, Duy Coung and Nidever, David L. and Pinsonneault, Marc and Shetrone, Matthew and Smee, Stephen and Smith, Verne V. and Stolberg

repository: sandorkruk/malatium

repo_name: sandorkruk/malatium