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Spectroscopic determination of masses (and implied ages) for red giants

Ness, M. and Hogg, David W. and Rix, H.-W. and Martig, M. and Pinsonneault, Marc H. and Ho, A. Y. Q. (2016) Spectroscopic determination of masses (and implied ages) for red giants. Astrophysical Journal, 823 (2). Art. No. 114. ISSN 0004-637X.

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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 [ɑ/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.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Ness, M.0000-0001-5082-6693
Hogg, David W.0000-0003-2866-9403
Rix, H.-W.0000-0003-4996-9069
Pinsonneault, Marc H.0000-0002-7549-7766
Ho, A. Y. Q.0000-0002-9017-3567
Additional Information:© 2016 The American Astronomical Society. Received 2015 October 13; accepted 2016 February 3; published 2016 May 27. It is a pleasure to thank Maria Bergemann (MPIA) John Bochanski (Rider), Morgan Fouesneau (MPIA), Ricardo Schiavon (Liverpool John Moores University), Dan Foreman- Mackey (UW), Amelia Stutz (MPIA), and Ben Weiner (Arizona State) for valuable discussions and contributions. This project made use of the NASA Astrophysics Data System and open-source code in the numpy and scipy packages. The research has received funding from the European Research Council under the European Union’s Seventh Framework Programme (FP 7) ERC Grant Agreement n. [321035]. We thank the Kavali Institute Theoretical Physics Galactic Archeology Program: this research was supported in part by the National Science Foundation under Grant No. NSF PHY11-25915. Funding for SDSS-III has been provided by the Alfred P. Sloan Foundation, the participating institutions, the National Science Foundation, and the U.S. Department of Energy Office of Science. The SDSS-III website is SDSS-III is managed by the Astrophysical Research Consortium for the participating institutions of the SDSS-III Collaboration, including the University of Arizona, the Brazilian Participation Group, Brookhaven National Laboratory, Carnegie Mellon University, the University of Florida, the French Participation Group, the German Participation Group, Harvard University, the Instituto de Astrofisica de Canarias, the Michigan State/Notre Dame/JINA Participation Group, Johns Hopkins University, Lawrence Berkeley National Laboratory, Max Planck Institute for Astrophysics, Max Planck Institute for Extraterrestrial Physics, New Mexico State University, New York University, Ohio State University, Pennsylvania State University, the University of Portsmouth, Princeton University, the Spanish Participation Group, the University of Tokyo, the University of Utah, Vanderbilt University, the University of Virginia, the University of Washington, and Yale University.
Funding AgencyGrant Number
European Research Council (ERC)321035
Alfred P. Sloan FoundationUNSPECIFIED
Participating InstitutionsUNSPECIFIED
Department of Energy (DOE)UNSPECIFIED
Subject Keywords:Galaxy: stellar content; methods: data analysis; methods: statistical; stars: evolution; stars: fundamental parameters; techniques: spectroscopic
Issue or Number:2
Record Number:CaltechAUTHORS:20160701-070902496
Persistent URL:
Official Citation:M. Ness et al 2016 ApJ 823 114
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:68797
Deposited By: Ruth Sustaita
Deposited On:01 Jul 2016 15:37
Last Modified:03 Oct 2019 10:16

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