CAREER: Fundamental properties of young and pre-main-sequence stars

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Stars form the foundation upon which much of modern astronomy rests and directly impact sub- fields as diverse as the cosmic distance scale, galaxy structure and evolution, the synthesis of chemical elements, planet formation, and the origin of life. Precise knowledge of basic stellar parameters such as mass, radius, age, and luminosity are thus essential. However, substantial gaps in this knowledge exist for young, low-mass stars due to the paucity of known eclipsing and astrometric binary stars among this population that enable accurate determinations of these quantities. The proposed research will derive accurate luminosities, radii, ages, and masses for young, low-mass stars using binary systems recently identified by Gaia, K2, and TESS surveys. This project will also support research activities by a graduate and several undergraduate students, as well as efforts by the principal investigator to develop interactive activities for astronomy courses and an interactive/multimedia-based exhibit based on this research for the Morehead Planetarium on the UNC Chapel Hill campus.The researchers will derive stellar parameters to better than 5% accuracy for 5-500 million year old K & M stars through the analysis of light curves in a sample of low-mass eclipsing and astrometric binary systems. This is a proven method that is routinely applied to older, more massive stars. Using these systems as ``benchmarks’’ they will derive empirical mass-luminosity-age relations, investigate the impact of magnetic activity on the derived parameters, and determine empirical relations for stellar radii, luminosity, and surface temperature from direct observables given an age. They will further explore age distributions in star clusters using spectroscopically determined lithium abundances and through explicit modeling of multiple populations. A major motivation of this work is to provide improved parameters for young planetary hosts, however the derived relations between direct observables and fundamental properties will be applicable to a wide variety of scientific applications.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.