Red giant masses and ages derived from carbon and nitrogen abundances

By M. Martig, Morgan Fouesneau, Hans-Walter Rix, M. Ness, Szabolcs Mészáros, D. A. García-Hernández, M. Pinsonneault, A. Serenelli, V. S. Aguirre, O. Zamora. 2015

181 citations recorded by the source corpus.

We show that the masses of red giant stars can be well predicted from their photospheric carbon and nitrogen abundances, in conjunction with their spectroscopic stellar labels log g, Teff, and [Fe/H]. This is qualitatively expected from mass-dependent post-main-sequence evolution. We here establish an empirical relation between these quantities by drawing on 1475 red giants with asteroseismic mass estimates from Kepler that also have spectroscopic labels from Apache Point Observatory Galactic Evolution Experiment (APOGEE) DR12. We assess the accuracy of our model, and find that it predicts stellar masses with fractional rms errors of about 14 per cent (typically 0.2 M⊙). From these masses, we derive ages with rms errors of 40 per cent. This empirical model allows us for the first time to make age determinations (in the range 1–13 Gyr) for vast numbers of giant stars across the Galaxy. We apply our model to ∼52 000 stars in APOGEE DR12, for which no direct mass and age information was previously available. We find that these estimates highlight the vertical age structure of the Milky Way disc, and that the relation of age with [α/M] and metallicity is broadly consistent with established expectations based on detailed studies of the solar neighbourhood.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/cfba31dafc1d5e80ef6238219855fe2d8e1f245c

How researchers see this paper

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In Astronomy and Astrophysics

1. Hans-Walter Rix
2. I. Minchev
3. Jo Bovy
4. Joss Bland-Hawthorn
5. C. Conroy
6. M. Martig
7. C. Chiappini
8. N. Evans II

In Instrumentation

1. I. Minchev
2. Hans-Walter Rix
3. Joss Bland-Hawthorn
4. Jo Bovy
5. C. Conroy
6. M. Martig
7. O. Gerhard
8. C. Chiappini

Citations in the corpus

• Measuring Radial Orbit Migration in the Galactic Disk (2018, methodology): “…data-driven approach to calibrate spectroscopic age estimates to asteroseismic data; the spectroscopic age signature of red clump giants resides in the C and N abundances (at given [Fe/H]), reflecting mass-dependent (and hence age-dependent) dredge-up (Masseron & Gilmore 2015; Martig et al. 2016).”
• CHEMICAL TAGGING CAN WORK: IDENTIFICATION OF STELLAR PHASE-SPACE STRUCTURES PURELY BY CHEMICAL-ABUNDANCE SIMILARITY (2016, background): “The stars in this structure are metal-rich and have a low [C/N] ratio and are therefore likely young (following the [C/N]–mass relationship; Martig et al. 2016).”
• PLATO as it is: a legacy mission for Galactic archaeology (2017, unknown): “7 The current observational evidence suggests the 𝛼 -rich disk to be systematically older than the 𝛼 -poor disk component (Fuhrmann 2011; Martig et al. 2016; Ness et al. 2016).”
• The Lives of Stars: Insights from the TGAS–RAVE–LAMOST Data Set (2018, methodology): “Some other specialized methods for measuring age exist, such as elemental abundance ratios in giants (Mar- tig et al. 2016), or astroseismic age-estimation for giants (Casagrande et al. 2016), but robust isochrone matched age-determination for the full range of stellar types had to wait until more…”
• The Payne: Self-consistent ab initio Fitting of Stellar Spectra (2018, background): “In fact, the [C/N] ratio has been shown to be an excellent indicator of stellar mass for giants (Martig et al. 2016; Ness et al. 2016; Ho et al. 2017); how much the dredge-up affects the [C/N] ratio depends crucially on the stellar mass.”
• The vertical metallicity gradients of mono-age stellar populations in the Milky Way with the RAVE and Gaia data (2017, methodology): “There are several ways to obtain the ages of stars, including isochrone fitting (e.g. Holmberg et al. 2009; Casagrande et al. 2011; Haywood et al. 2013), asteroseismology (e.g. Chaplin & Miglio 2013, for a review) and the C/N abundance ratio (Masseron & Gilmore 2015; Martig et al. 2016).”
• THE RELATIONSHIP BETWEEN MONO-ABUNDANCE AND MONO-AGE STELLAR POPULATIONS IN THE MILKY WAY DISK (2016, methodology): “An initial central component is formed during an early epoch of violent merger activity, where gas-rich mergers supply the initial reservoir of gas at high redshift and merger activity decreases with redshift, similarly to what is expected for the Milky Way.”
• Co-formation of the disc and the stellar halo (2018, background): “…disc is bracketed to have happened between ∼8 and ∼11 Gyr ago, based on white dwarf cooling ages (see Oswalt et al. 1996; Leggett et al. 1998; Knox et al. 1999; Kilic et al. 2017), isochrone modelling (e.g. Haywood et al. 2013; Martig et al. 2016) and nucleocosmochronology (del Peloso et al. 2005).”
• Confirming chemical clocks: asteroseismic age dissection of the Milky Way disc(s) (2017, methodology): “Martig et al. (2016) showed that the carbon and nitrogen abundances in these giants, altered in their photospheres during the first dredge-up, could be calibrated using the masses derived from asteroseismology to provide a spectroscopic measurement of (implied) ages with a precision of ∼0.2 dex and…”
• Binary Companions of Evolved Stars in APOGEE DR14: Search Method and Catalog of ∼5000 Companions (2018, background): “The subset of RC stars are even more powerful because they are standard candles and have masses that can be estimated using spectroscopy (using dredged-up elements; Martig et al. 2016; Ness et al. 2016).”
• A NEW GENERATION OF PARSEC-COLIBRI STELLAR ISOCHRONES INCLUDING THE TP-AGB PHASE (2017, background): “Such a relation is nowadays, directly or indirectly, being used to constrain ages of field MW stars (see Masseron & Gilmore 2015; Ness et al. 2016; Martig et al. 2016).”
• A RADIAL AGE GRADIENT IN THE GEOMETRICALLY THICK DISK OF THE MILKY WAY (2016, background): “Two studies (Martig et al. 2016, hereafter M16; Ness et al. 2016b, hereafter N16) have recently (and for the first time) determined ages for stars over a large volume of the Galaxy within the Apache Point Observatory Galactic Evolution Experiment (APOGEE) survey (Majewski et al. 2015).”
• The GALAH survey: observational overview and Gaia DR1 companion (2016, background): “In particular, spectroscopic stellar surveys are revolutionising our understanding of Galactic structure and evolution (e.g., Helmi 2008; Rix & Bovy 2013; Hayden et al. 2014; Hayden et al. 2015; Martig et al. 2016).”
• The Second APOKASC Catalog: The Empirical Approach (2018, methodology): “APOKASC-1 data was used to calibrate mass using both [C/N] (Martig et al. 2016) and the full APOGEE spectra (Ness et al. 2016) using the CANNON methodology.”
• The age–metallicity structure of the Milky Way disc using APOGEE (2017, methodology): “It is also important to account for all other cuts made by Martig et al. (2016b) on the stellar parameters in the APOGEE catalogue, outlined in full at the beginning of their Section 6.2.”