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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents

ID: 731877.0, MPI für Astronomie / Publikationen_mpia
Spectroscopic determination of masses (and implied ages) for red giants
Authors:Ness, M.; Hogg, D. W.; Rix, H. -. W.; Martig, M.; Pinsonneault, M. H.; Ho, A. Y. Q.
Date of Publication (YYYY-MM-DD):2016
Title of Journal:The Astrophysical Journal
Issue / Number:2
Start Page:id. 114 (19 pp)
Audience:Not Specified
Abstract / Description:The mass of a star is arguably its most fundamental parameter. For red giant stars, tracers luminous enough to be observed across the Galaxy, mass implies a stellar evolution age. It has proven to be extremely difficult to infer ages and masses directly from red giant spectra using existing methods. From the Kepler and apogee surveys, samples of several thousand stars exist with high-quality spectra and asteroseismic masses. Here we show that from these data we can build a data-driven spectral model using The Cannon, which can determine stellar masses to ∼0.07 dex from apogee dr12 spectra of red giants; these imply age estimates accurate to ∼0.2 dex (40%). We show that The Cannon constrains these ages foremost from spectral regions with CN absorption lines, elements whose surface abundances reflect mass-dependent dredge-up. We deliver an unprecedented catalog of 70,000 giants (including 20,000 red clump stars) with mass and age estimates, spanning the entire disk (from the Galactic center to R∼ 20 kpc). We show that the age information in the spectra is not simply a corollary of the birth-material abundances {{[Fe/H]}} and [α /{Fe}], and that, even within a monoabundance population of stars, there are age variations that vary sensibly with Galactic position. Such stellar age constraints across the Milky Way open up new avenues in Galactic archeology.
Free Keywords:Galaxy: stellar content; methods: data analysis; methods: statistical; stars: evolution; stars: fundamental parameters; techniques: spectroscopic
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:ISSN:0004-637X %R 10.3847/0004-637X/823/2/114
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