Dissertations, Theses, and Capstone Projects

Date of Degree

9-2021

Document Type

Dissertation

Degree Name

Ph.D.

Program

Physics

Advisor

Kelle Cruz

Advisor

Jacqueline K. Faherty

Committee Members

Ruth Angus

Emily L. Rice

Sarah Schmidt

Ari Maller

Subject Categories

Stars, Interstellar Medium and the Galaxy

Keywords

Low-mass stars, Ages, Bayesian Analysis, Magnetic activity, Open source code, White dwarfs

Abstract

Estimating ages of M dwarfs, the lowest mass stars in the Galaxy, is a current unresolved problem in Astrophysics. This dissertation focuses on developing a method to estimate ages for M dwarfs. This method consists of combining different age indicators in a Bayesian framework to achieve a precise age measurement. The age indicators I use are: 1) position in the color-magnitude diagram which is a proxy for effective temperature and luminosity, 2) movement of the stars in the Galaxy, or its 3D kinematics, 3) magnetic activity, measured by the Halpha emission line of the spectrum. In this dissertation I analyze the dependence of these indicators with age, and the correlations between each other. Using these relations, I write mdwarfdate, an open source Python code that estimates ages of M dwarfs. I confirm the robustness of the code by testing it on a simulated sample of stars, and examining a set of age calibrators. Using this method, I estimate ages for a sample of stars with rotation period measurements –another age indicator– and I analyze the relation between rotation period and age. This study will allow me to include rotation period as an age indicator in the code, which will improve the precision of the age estimation, and is the next step in this work.

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