Bibcode
Hasselquist, S.; Holtzman, Jon; Tayar, Jamie; Shetrone, Matthew; Johnson, Jennifer; Weinberg, David; Bird, Jonathan; Fernandez-Trincado, Jose; Feuillet, Diane; Hearty, Fred; Lane, Richard; Villanova, Sandro; Zamora, O.; APOGEE team
Referencia bibliográfica
American Astronomical Society, AAS Meeting #231, id.#411.02
Fecha de publicación:
1
2018
Número de citas
0
Número de citas referidas
0
Descripción
The Apache Point Observatory Galactic Evolution Experiment (APOGEE)
provides precise carbon and nitrogen abundances for over 100,000 red
giant stars across the Milky Way Galaxy (MW). Recently, it has been
shown that the carbon-to-nitrogen ratio (often expressed as [C/N]) can
be indicative of the mass of a red giant star, from which an age can be
inferred. In this work, we reaffirm that [C/N] can be used as a mass
indicator for APOGEE red giants from Data Release 14 (DR14) and present
[C/N] vs. [Fe/H] abundance tracks for red giants star across the MW (3
< R < 15 kpc). We derive empirical age tracks in the [C/N]-[Fe/H]
plane using ages derived from seismic masses in the APOKASC catalog to
interpret these abundance tracks as tracks in age. Similar to what has
been found in other studies, we find a range of ages across all
metallicities for stars in the plane of the Galaxy along with an age
gradient for stars above the plane (|Z| > 1.0 kpc). We trace the
youngest stars in the APOGEE sample and find a metallicity gradient in
[Fe/H] of -0.074 dex/kpc across the Galaxy from 6 kpc to 12 kpc. This is
in agreement with the gradient found over a similar radial range using
young stars of the CoRoGEE sample (Anders et al. 2017). Additionally, we
find that the more metal-rich stars located in the plane of the outer
Galaxy (R > 7 kpc) tend to exhibit enhanced [C/N] relative to the
more metal-poor stars, indicating that the metal-rich stars are actually
older. We explore possible formation scenarios of these stars and find
that radial migration is a plausible explanation for their current
location in the Galaxy.