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How to Constrain Your M Dwarf: Measuring Effective Temperature, Bolometric Luminosity, Mass, and Radius
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Theoretical Astrophysics. (Theoretical Astrophysics)ORCID iD: 0000-0002-2012-7215
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2015 (English)In: Astrophysical Journal, ISSN 0004-637X, E-ISSN 1538-4357, Vol. 804, 64Article in journal (Refereed) Published
Abstract [en]

Precise and accurate parameters for late-type (late K and M) dwarf stars are important for characterization of any orbiting planets, but such determinations have been hampered by these stars' complex spectra and dissimilarity to the Sun. We exploit an empirically calibrated method to estimate spectroscopic effective temperature (Teff) and the Stefan--Boltzmann law to determine radii of 183 nearby K7--M7 single stars with a precision of 2%--5%. Our improved stellar parameters enable us to develop model-independent relations between Teff or absolute magnitude and radius, as well as between color and Teff. The derived Teff--radius relation depends strongly on [Fe/H], as predicted by theory. The relation between absolute KS magnitude and radius can predict radii accurate to ~= 3%. We derive bolometric corrections to the V{{R}C}{{I}C}grizJH{{K}S} and Gaia passbands as a function of color, accurate to 1%--3%. We confront the reliability of predictions from Dartmouth stellar evolution models using a Markov chain Monte Carlo to find the values of unobservable model parameters (mass, age) that best reproduce the observed effective temperature and bolometric flux while satisfying constraints on distance and metallicity as Bayesian priors. With the inferred masses we derive a semi-empirical mass--absolute magnitude relation with a scatter of 2% in mass. The best-agreement models overpredict stellar Teff values by an average of 2.2% and underpredict stellar radii by 4.6%, similar to differences with values from low-mass eclipsing binaries. These differences are not correlated with metallicity, mass, or indicators of activity, suggesting issues with the underlying model assumptions, e.g., opacities or convective mixing length.

Place, publisher, year, edition, pages
2015. Vol. 804, 64
Keyword [en]
planetary systems, stars: abundances, stars: fundamental parameters, stars: late-type, stars: low-mass, stars: statistics
National Category
Astronomy, Astrophysics and Cosmology
Research subject
URN: urn:nbn:se:uu:diva-253741DOI: 10.1088/0004-637X/804/1/64ISI: 000354189500064OAI: diva2:815894

Erratum in Astrophysical Journal 819(1) article number 87.  DOI: 10.3847/0004-637X/819/1/87

Available from: 2015-06-02 Created: 2015-06-02 Last updated: 2016-07-13Bibliographically approved

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