Age-relations for low-mass stars

Rocio Kiman (CUNY/AMNH)
Friday, March 19, 2021 - 2:00pm to 3:00pm

Stellar age is a key fundamental property for understanding the history, evolution, and future of stellar populations, the Milky Way, and exoplanets. However, age is extremely difficult to measure for individual stars. Low-mass stars, or M dwarfs, are the most numerous stars in the Galaxy, they have lifetimes longer than the current age of the Universe, and are likely to host the majority of Earth-like exoplanets. For this reason, these main sequence stars are ideal for studying the Milky Way and exoplanets properties in a wide range of ages. Ages of M dwarfs are especially difficult to estimate because methods used for solar-type stars break down as lower mass objects become fully convective. Empirical and statistical methods are required to constrain the ages of M dwarfs. 
I want to build a robust Bayesian algorithm to infer ages of M dwarfs from the following age indicators: 1) Position in the color–magnitude diagram; 2) Magnetic activity, as indicated by the H-alpha emission line; 3) Full kinematics, taking advantage of Gaia DR2 and DR3; 4) Rotation periods. I will present the age-calibrations I did of these age indicators, including the age-activity relation for the H-alpha emission line. I will show the empirical age-activity relation I obtained, which indicates that H-alpha equivalent widths decrease with age. I will also explain how I am going to use this relation to obtain precise age estimation of M dwarfs. 

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