J/ApJ/817/40 High-resolution NIR spectra of local giants (Feuillet+, 2016)
Determining ages of APOGEE giants with known distances.
Feuillet D.K., Bovy J., Holtzman J., Girardi L., MacDonald N.,
Majewski S.R., Nidever D.L.
<Astrophys. J., 817, 40 (2016)>
=2016ApJ...817...40F 2016ApJ...817...40F (SIMBAD/NED BibCode)
ADC_Keywords: Stars, nearby ; Magnitudes, absolute ; Stars, ages ;
Spectra, infrared ; Effective temperatures ; Abundances
Keywords: Galaxy: disk; Galaxy: evolution; stars: abundances;
stars: fundamental parameters
Abstract:
We present a sample of 705 local giant stars observed using the New
Mexico State University 1m telescope with the Sloan Digital Sky
Survey-III/Apache Point Observatory Galactic Evolution Experiment
(APOGEE) spectrograph, for which we estimate stellar ages and the
local star formation history (SFH). The high-resolution (R∼22500),
near infrared (1.51-1.7µm) APOGEE spectra provide measurements of
stellar atmospheric parameters (temperature, surface gravity, [M/H],
and [α/M]). Due to the smaller uncertainties in surface gravity
possible with high-resolution spectra and accurate Hipparcos distance
measurements, we are able to calculate the stellar masses to within
30%. For giants, the relatively rapid evolution up the red giant
branch allows the age to be constrained by the mass. We examine
methods of estimating age using both the mass-age relation directly
and a Bayesian isochrone matching of measured parameters, assuming a
constant SFH. To improve the SFH prior, we use a hierarchical modeling
approach to constrain the parameters of the model SFH using the age
probability distribution functions of the data. The results of an
α-dependent Gaussian SFH model show a clear age-[α/M]
relation at all ages. Using this SFH model as the prior for an
empirical Bayesian analysis, we determine ages for individual stars.
The resulting age-metallicity relation is flat, with a slight decrease
in [M/H] at the oldest ages and a ∼0.5 dex spread in metallicity
across most ages. For stars with ages ≲1Gyr we find a smaller spread,
consistent with radial migration having a smaller effect on these
young stars than on the older stars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 120 706 Parameters of the local sample of giants
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See also:
III/272 : RAVE 4th data release (Kordopatis+, 2013)
V/137 : Extended Hipparcos Compilation (XHIP) (Anderson+, 2012)
V/130 : Geneva-Copenhagen Survey of Solar neighbourhood III (Holmberg+, 2009)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
I/239 : The Hipparcos and Tycho Catalogues (ESA 1997)
J/A+A/562/A71 : Abundances of solar neighbourhood dwarfs (Bensby+, 2014)
J/ApJ/764/78 : Oxygen abundances in nearby FGK stars (Ramirez+, 2013)
J/A+A/545/A32 : Chemical abundances of 1111 FGK stars (Adibekyan+, 2012)
J/AJ/137/4377 : List of SEGUE plate pairs (Yanny+, 2009)
J/A+A/497/497 : Physical parameters from JHK flux (Gonzalez-Hernandez+, 2009)
J/MNRAS/367/1329 : Elemental abundances for 176 stars (Reddy+, 2006)
J/A+AS/102/603 : Chemical evolution of the galactic disk II. (Edvardsson+ 1993)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- --- [2M]
3- 18 A16 --- 2MASS 2MASS identifier (HHMMSSss+DDMMSSs; J2000)
20- 25 I6 --- HIP Hipparcos Catalog identifier
27- 30 I4 K Teff [3895/5349] Effective temperature
32- 33 I2 K e_Teff [92] Uncertainty in Teff
35- 38 F4.2 [cm/s2] log(g) [0.7/3.8] Surface gravity
40- 43 F4.2 [cm/s2] e_log(g) [0.11] Uncertainty in log(g)
45- 49 F5.2 [-] [M/H] [-1/0.6] Metallicity
51- 54 F4.2 [-] e_[M/H] [0.05] Uncertainty in [M/H]
56- 60 F5.2 [-] [a/M] [-0.04/0.3] Alpha element abundance
62- 65 F4.2 [-] e_[a/M] [0.05] Uncertainty in [alpha/M]
67- 71 F5.2 mag VTMag [-3.1/4.3] Absolute Tycho V magnitude
73- 76 F4.2 mag e_VTMag [0.02/0.3] Uncertainty in VTMag
78- 82 F5.2 Msun Mass [0.4/24] Derived mass
84- 87 F4.2 Msun e_Mass [0.1/8] Uncertainty in mass
89- 93 F5.2 [yr] AgeM [8/10.2] log age derived from mass-age relation
95- 98 F4.2 [yr] e_AgeM [0.3/0.5] Uncertainty in AgeM
100-104 F5.2 [yr] AgeB [8/10.1] log age from Bayesian analysis
106-109 F4.2 [yr] e_AgeB [0/0.4] Uncertainty in AgeB
111-115 F5.2 [yr] AgeE [8.1/10.1] log age from empirical Bayesian
analysis
117-120 F4.2 [yr] e_AgeE [0/0.5] Uncertainty in AgeE
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 05-Apr-2016