An Intermediate-age Alpha-rich Galactic Population in K2
- Author(s)
- Jack T. Warfield, Joel C. Zinn, Marc H. Pinsonneault, Jennifer A. Johnson, Dennis Stello, Thomas Kallinger
- Abstract
We explore the relationships between the chemistry, ages, and locations of stars in the Galaxy using asteroseismic data from the K2 mission and spectroscopic data from the Apache Point Galactic Evolution Experiment survey. Previous studies have used giant stars in the Kepler field to map the relationship between the chemical composition and the ages of stars at the solar circle. Consistent with prior work, we find that stars with high [α/Fe] have distinct, older ages in comparison to stars with low [α/Fe]. We provide age estimates for red giant branch (RGB) stars in the Kepler field, which support and build upon previous age estimates by taking into account the effect of α-enrichment on opacity. Including this effect for [α/Fe]-rich stars results in up to 10% older ages for low-mass stars relative to corrected solar mixture calculations. This is a significant effect that Galactic archeology studies should take into account. Looking beyond the Kepler field, we estimate ages for 735 RGB stars from the K2 mission, mapping age trends as a function of the line of sight. We find that the age distributions for low- and high-[α/Fe] stars converge with increasing distance from the Galactic plane, in agreement with suggestions from earlier work. We find that K2 stars with high [α/Fe] appear to be younger than their counterparts in the Kepler field, overlapping more significantly with a similarly aged low-[α/Fe] population. This observation may suggest that star formation or radial migration proceeds unevenly in the Galaxy.
- Organisation(s)
- Department of Astrophysics
- External organisation(s)
- Ohio State University, University of Virginia, University of New South Wales, ARC Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), The University of Sydney, Aarhus University
- Journal
- The Astronomical Journal
- Volume
- 161
- No. of pages
- 12
- ISSN
- 0004-6256
- DOI
- https://doi.org/10.3847/1538-3881/abd39d
- Publication date
- 03-2021
- Peer reviewed
- Yes
- Austrian Fields of Science 2012
- 103003 Astronomy, 103004 Astrophysics
- Keywords
- ASJC Scopus subject areas
- Astronomy and Astrophysics, Space and Planetary Science
- Portal url
- https://ucrisportal.univie.ac.at/en/publications/6a5f2701-84d1-4769-8086-cb9acbc40673