M. Ness, David W. Hogg, H. W. Rix, M. Martig, Marc H. Pinsonneault, A. Y.Q. Ho

    Research output: Contribution to journalArticlepeer-review


    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 kpc). We show that the age information in the spectra is not simply a corollary of the birth-material abundances and , 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.

    Original languageEnglish (US)
    Article number114
    JournalAstrophysical Journal
    Issue number2
    StatePublished - Jun 1 2016


    • Galaxy: stellar content
    • methods: data analysis
    • methods: statistical
    • stars: evolution
    • stars: fundamental parameters
    • techniques: spectroscopic

    ASJC Scopus subject areas

    • Astronomy and Astrophysics
    • Space and Planetary Science


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