Chemical abundances of open clusters using the cannon: application to improve calibration of asteroseismic ages

Abstract

Precise stellar ages for field stars or stars that are not gravitationally bound to other stars are still elusive today. If precise ages were able to be determined, they would have a significant impact on our understanding of the history of stellar formation in the Milky Way. It would also provide a basis for understanding stellar formation in other galaxies as well. More accurate ages of halo stars, thought to be the oldest stars in the Milky Way, could provide an even better limit on the age of the universe itself. Determining these ages with better precision is crucial to our understanding of the universe. Current methods to determine age estimates of stars, such as spectroscopy and asteroseismology, individually have very large uncertainties. Combining these two age estimation methods would significantly reduce this uncertainty. In this dissertation, metallicites and asteroseismology data for a set of open clusters are combined to produce a new asteroseismic age-metallicity-mass relation to reduce the uncertainty in age estimates of stars. Open clusters are the ideal age calibrator, however few have good asteroseismic data. To date, there have been no larger scale surveys of open clusters that compare asteroseismology and spectroscopy estimates of stellar ages, due to the limits of area coverage from the Kepler mission. The approach of this study is to more than double the number of clusters with high-quality asteroseismology and high-resolution abundance determinations by observing a sample of 10 open clusters. These clusters were chosen as they overlapped with Kepler 2 (K2) campaign fields to utilize the asteroseismology observations of giant stars in the K2 fields. We analyze the clusters and use The Cannon to measure abundances of [Fe/H], [Mg/Fe], [Si/Fe], [Ni/Fe], [Ca/Fe], [Na/Fe],and [V/Fe] and determine cluster membership. Using this sample, we present a new asteroseismic age-metallicity-mass relation that improves the age precision for Milky Way disk field stars using asteroseismology.