J/MNRAS/456/3655 Masses and ages of red giants (Martig+, 2016)
Red giant masses and ages derived from carbon and nitrogen abundances.
Martig M., Fouesneau M., Rix H.-W., Ness M., Meszaros S.,
Garcia-Hernandez D.A., Pinsonneault M., Serenelli A., Silva Aguirre V.,
Zamora O.
<Mon. Not. R. Astron. Soc., 456, 3655-3670 (2016)>
=2016MNRAS.456.3655M 2016MNRAS.456.3655M (SIMBAD/NED BibCode)
ADC_Keywords: Stars, giant ; Stars, ages ; Stars, masses
Keywords: stars: abundances - stars: evolution - stars: fundamental parameters
Abstract:
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 logg, 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 percent (typically
0.2M☉). From these masses, we derive ages with rms errors of 40
percent. This empirical model allows us for the first time to make age
determinations (in the range 1-13Gyr) for vast numbers of giant stars
across the Galaxy. We apply our model to ∼52000 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.
Description:
The APOKASC project is the spectroscopic follow-up by APOGEE (Majewski
et al. 2015, in prep., as part of the third phase of the Sloan Digital
Sky Survey, SDSS-III; Eisenstein et al., 2011AJ....142...72E 2011AJ....142...72E) of stars
with asteroseismology data from the Kepler Asteroseismic Science
Consortium (KASC). The first version of the APOKASC catalogue
(Pinsonneault et al., 2014, Cat. J/ApJS/215/19) contains seismic and
spectroscopic measurements for 1989 giants, with the spectroscopic
information corresponding to APOGEE's Data Release 10 (DR10; Ahn et
al., 2014ApJS..211...17A 2014ApJS..211...17A). In this work, we keep the same original
sample of 1989 stars and their seismic parameters, but update their
Teff and abundances to DR12 values (Alam et al., 2015ApJS..219...12A 2015ApJS..219...12A;
Holtzman et al., 2015AJ....150..148H 2015AJ....150..148H).
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 79 1475 Stellar parameters for stars in the training set,
together with their "true" masses and ages as well
as the masses and ages predicted by our models
table2.dat 55 52286 Predicted masses and ages for stars in APOGEE DR12
--------------------------------------------------------------------------------
See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
Byte-by-byte Description of file: table1.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 A2 --- --- [2M]
3- 18 A16 --- 2MASS 2MASS name (HHMMSSss+DDMMSSs)
20- 23 I4 K Teff Effective temperature
25- 27 F3.1 [cm/s2] logg Surface gravity
29- 33 F5.2 [-] [M/H] Metallicity, [M/H]
35- 39 F5.2 --- [C/M] Carbon abundance
41- 45 F5.2 --- [N/M] Nitrogen abundance
47- 50 F4.2 Msun Massin True mass
52- 55 F4.2 Msun e_Massin rms uncertainty on Min
57- 60 F4.2 Msun Massout Predicted mass
62- 65 F4.1 Gyr Agein True age
67- 69 F3.1 Gyr e_Agein Error on Agein (lower value)
71- 74 F4.1 Gyr E_Agein Error on Agein (upper value)
76- 79 F4.1 Gyr Ageout Predicted age
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 2 A2 --- --- [2M]
3- 18 A16 --- 2MASS 2MASS name (HHMMSSss+DDMMSSs)
20- 23 I4 K Teff Effective temperature
25- 27 F3.1 [cm/s2] logg Surface gravity
29- 33 F5.2 [-] [M/H] Metallicity, [M/H]
35- 39 F5.2 --- [C/M] Carbon abundance
41- 45 F5.2 --- [N/M] Nitrogen abundance
47- 50 F4.2 Msun Massout Predicted mass
52- 55 F4.1 Gyr Ageout Predicted age
--------------------------------------------------------------------------------
History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 06-Oct-2016