J/AJ/161/100 Ages and alpha-abundances of population in K2 (Warfield+, 2021)
An intermediate-age Alpha-rich galactic population in K2.
Warfield J.T., Zinn J.C., Pinsonneault M.H., Johnson J.A., Stello D.,
Elsworth Y., Garcia R.A., Kallinger T., Mathur S., Mosser B., Beaton R.L.,
Garcia-Hernandez D.A.
<Astron. J., 161, 100 (2021)>
=2021AJ....161..100W 2021AJ....161..100W
ADC_Keywords: Surveys; Milky Way; Stars, ages; Stars, masses; Stars, giant;
Abundances; Effective temperatures; Spectra, infrared
Keywords: Stellar ages ; Stellar abundances ; Asteroseismology ;
Galaxy evolution ; Galaxy formation ; Milky Way formation ;
Galaxy stellar content ; Red giant stars ; Surveys
Abstract:
We explore the relationships between the chemistry, ages, and
locations of stars in the Galaxy using asteroseismic data from the K2
mission and spectroscopic data from the Apache Point Galactic
Evolution Experiment survey. Previous studies have used giant stars in
the Kepler field to map the relationship between the chemical
composition and the ages of stars at the solar circle. Consistent with
prior work, we find that stars with high [α/Fe] have distinct,
older ages in comparison to stars with low [α/Fe]. We provide
age estimates for red giant branch (RGB) stars in the Kepler field,
which support and build upon previous age estimates by taking into
account the effect of α-enrichment on opacity. Including this
effect for [α/Fe]-rich stars results in up to 10% older ages for
low- mass stars relative to corrected solar mixture calculations. This
is a significant effect that Galactic archeology studies should take
into account. Looking beyond the Kepler field, we estimate ages for
735 RGB stars from the K2 mission, mapping age trends as a function of
the line of sight. We find that the age distributions for low- and
high-[α/Fe] stars converge with increasing distance from the
Galactic plane, in agreement with suggestions from earlier work. We
find that K2 stars with high [α/Fe] appear to be younger than
their counterparts in the Kepler field, overlapping more significantly
with a similarly aged low-[α/Fe] population. This observation
may suggest that star formation or radial migration proceeds unevenly
in the Galaxy.
Description:
The spectroscopic data for this work is from the sixteenth data
release of the APOGEE survey. This survey has been collecting
high-resolution infrared spectra for hundreds of thousand of stars
throughout the Milky Way. The spectroscopic data in APOGEE DR16 was
collected with the 2.5m Sloan Foundation Telescope at the Apache Point
Observatory in New Mexico, USA and the 2.5m du Pont Telescope at Las
Campanas Observatory in Chile as a part of SDSS-IV. APOGEE uses twin
R∼22500 H-band spectrographs.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table3.dat 450 805 Data for K2 campaigns 4, 6, and 7, including our
ages
table4.dat 190 2407 RGB stars in the Kepler field, including our ages
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See also:
V/133 : Kepler Input Catalog (Kepler Mission Team, 2009)
I/337 : Gaia DR1 (Gaia Collaboration, 2016)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
III/284 : APOGEE-2 data from DR16 (Johnsson+, 2020)
J/A+A/410/527 : Abundances in the Galactic disk (Bensby+, 2003)
J/ApJ/746/16 : Modelling the convection zone (van Saders+, 2012)
J/ApJS/215/19 : APOKASC catalog of Kepler red giants (Pinsonneault+, 2014)
J/MNRAS/445/2758 : KIC giants Bayesian dist. & extinctions (Rodrigues+, 2014)
J/MNRAS/452/2127 : Fundamental parameters of Kepler stars (Silva Aguirre+,2015)
J/AJ/151/144 : ASPCAP weights for 15 APOGEE chemic. elements (Garcia+,2016)
J/A+A/597/A30 : Seismology & spectroscopy of CoRoGEE red giants (Anders+,2017)
J/ApJ/844/102 : KIC star plxs from asteroseismology vs Gaia (Huber+, 2017)
J/ApJ/835/173 : Kepler asteroseismic LEGACY sample. II. (Silva Aguirre+, 2017)
J/ApJ/835/83 : K2 GAP data release. I. Campaign 1 (Stello+, 2017)
J/ApJS/239/32 : APOKASC-2 catalog of Kepler evolved stars (Pinsonneault+,2018)
J/AJ/156/18 : APOGEE DR14:Binary comp. of evolved stars (Price-Whelan+,2018)
J/A+A/627/A173 : Abundances for 4 metal-poor stars (Valentini+, 2019)
J/ApJS/251/23 : K2 GAP DR2: campaigns 4, 6 & 7 (Zinn+, 2020)
J/A+A/645/A85 : Age dissection of the Milky Way discs (Miglio+, 2021)
Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 11 F11.1 --- K2 K2 object ID
13- 13 I1 --- K2camp [4/7] K2 campaign field
15- 32 A18 --- APOGEE APOGEE object ID
34- 39 F6.2 Gyr Age [0.14/652] Median calculated stellar age
41- 46 F6.2 Gyr e_Age [0/457] Lower 1-sigma deviation on stellar
age
48- 54 F7.2 Gyr E_Age [0/4998] Upper 1-sigma deviation on stellar
age
56- 74 F19.15 deg RAdeg [51.6/291] Right Ascension (J2000)
76- 94 F19.15 deg DEdeg [-29.6/26.2] Declination (J2000)
96-123 A28 --- GAIA Object GAIA designation
125-133 F9.4 K Teff [3732/5304] Corrected effective temperature
from APOGEE DR16
135-144 F10.6 K e_Teff [60/158] Uncertainty on Teff
146-153 F8.6 [cm/s2] logg [0.67/3.19] Corrected log surface gravity
from APOGEE DR16
155-162 F8.6 [cm/s2] e_logg [0.03/0.12] Uncertainty on corrected logg
164-171 F8.6 [Sun] [alpha/M] [0.0002/0.39] Alpha abundance from APOGEE
DR16
173-180 F8.6 [Sun] e_[alpha/M] [0.004/0.04] Uncertainty on [alpha/M]
182-190 F9.6 [Sun] [Fe/H] [-1.9/0.43] Metallicity from APOGEE DR16
192-199 F8.6 [Sun] e_[Fe/H] [0.005/0.04] Uncertainty on [Fe/H]
201-207 F7.3 uHz numax [6.57/207] Mean value of numax from all
pipelines that returned a value from K2GAP
209-213 F5.3 uHz e_numax [0.024/2.66] Uncertainty on numax
215-220 F6.3 uHz dnu [1.07/16.6]? Mean value of dnu from all
pipelines that returned a value from K2GAP
222-226 F5.3 uHz e_dnu [0/0.32]? Uncertainty on dnu
228-234 F7.3 uHz numax.COR [6.47/207]? Corrected numax from the COR
pipeline from K2GAP
236-240 F5.3 uHz e_numax.COR [0.23/3.39]? Uncertainty on numax.COR
242-248 F7.3 uHz numax.A2Z [6.16/183]? Corrected numax from the A2Z
pipeline from K2GAP
250-255 F6.3 uHz e_numax.A2Z [0.34/23]? Uncertainty on numax.A2Z
257-263 F7.3 uHz numax.BAM [7.07/185]? Corrected numax from the BAM
pipeline from K2GAP
265-269 F5.3 uHz e_numax.BAM [0.18/3.8]? Uncertainty on numax.BAM
271-277 F7.3 uHz numax.CAN [7.78/176]? Corrected numax from the CAN
pipeline from K2GAP
279-283 F5.3 uHz e_numax.CAN [0.25/3.4]? Uncertainty on numax.CAN
285-291 F7.3 uHz numax.BHM [9.94/181]? Corrected numax from the BHM
pipeline from K2GAP
293-297 F5.3 uHz e_numax.BHM [0.19/3.3]? Uncertainty on numax.BHM
299-305 F7.3 uHz numax.SYD [7.44/207]? Corrected numax from the SYD
pipeline from K2GAP
307-312 F6.3 uHz e_numax.SYD [0.12/36]? Uncertainty on numax.SYD
314-319 F6.3 uHz dnu.COR [1.05/16.4]? Corrected dnu from the COR
pipeline from K2GAP
321-325 F5.3 uHz e_dnu.COR [0.05/0.23]? Uncertainty on dnu.COR
327-332 F6.3 uHz dnu.A2Z [1.23/15.5]? Corrected dnu from the A2Z
pipeline from K2GAP
334-338 F5.3 uHz e_dnu.A2Z [0.01/0.87]? Uncertainty on dnu.A2Z
340-345 F6.3 uHz dnu.BAM [1.24/14.4]? Corrected dnu from the BAM
pipeline from K2GAP
347-351 F5.3 uHz e_dnu.BAM [0.005/1.4]? Uncertainty on dnu.BAM
353-358 F6.3 uHz dnu.CAN [1.09/14]? Corrected dnu from the CAN
pipeline from K2GAP
360-364 F5.3 uHz e_dnu.CAN [0.009/0.36]? Uncertainty on dnu.CAN
366-371 F6.3 uHz dnu.BHM [1.48/14.9]? Corrected dnu from the BHM
pipeline from K2GAP
373-377 F5.3 uHz e_dnu.BHM [0.05/0.95]? Uncertainty on dnu.BHM
379-384 F6.3 uHz dnu.SYD [1.47/14.4]? Corrected dnu from the SYD
pipeline from K2GAP
386-390 F5.3 uHz e_dnu.SYD [0.02/0.84]? Uncertainty on dnu.SYD
392-396 F5.3 [cm/s2] logg.SEIS [1.71/3.23] Asteroseismic log surface
gravity
398-402 F5.3 [cm/s2] e_logg.SEIS [0.004/0.04] Uncertainty on logg.SEIS
404-408 F5.3 solMass Mass [0.3/3.67] Asteroseismic mass
410-414 F5.3 solMass e_Mass [0.03/1.1]? Uncertainty on Mass
416-420 F5.2 kpc Dist [0.33/11.4] Distance calculated from GAIA
parallax from Bailer-Jones 2015
422-425 F4.2 kpc e_Dist [0.01/7.4] Uncertainty on Dist
427-432 F6.2 kpc X [-12.3/-1.04] Galactocentric X coordinate
calculated with astropy
434-438 F5.2 kpc Y [-4.26/1.4] Galactocentric Y coordinate
calculated with astropy
440-444 F5.2 kpc Z [-2.37/8.66] Galactocentric Z coordinate
calculated with astropy
446-450 F5.2 kpc R [1.59/12.31] Galactocentric R coordinate
calculated with astropy
--------------------------------------------------------------------------------
Byte-by-byte Description of file: table4.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 I8 --- KIC MAST Kepler Input Catalog ID
10- 27 A18 --- APOGEE APOGEE object ID
29- 34 F6.2 Gyr Age [0.28/150] Median calculated stellar age
36- 40 F5.2 Gyr e_Age [0.02/88] Lower 1-sigma deviation on Age
42- 47 F6.2 Gyr E_Age [0.03/400] Upper 1-sigma deviation on Age
49- 53 F5.2 Gyr Age.APO [0.4/17.7] Calculated stellar age from
Pinsonneault et al. 2018
55- 63 F9.4 K Teff [3942/5239] Corrected effective temperature
from APOGEE DR16
65- 74 F10.6 K e_Teff [65/130] Uncertainty on Teff
76- 83 F8.6 [cm/s2] logg [1.41/3.35] Corrected log surface gravity
from APOGEE DR16
85- 92 F8.6 [cm/s2] e_logg [0.02/0.12] Uncertainty on logg
94-101 F8.6 [Sun] [alpha/M] [6e-06/0.39] Alpha abundance from APOGEE
DR16
103-110 F8.6 [Sun] e_[alpha/M] [0.004/0.03] Uncertainty on [alpha/M]
112-120 F9.6 [Sun] [Fe/H] [-2.15/0.45] Metallicity from APOGEE DR16
122-129 F8.6 [Sun] e_[Fe/H] [0.005/0.03] Uncertainty on [Fe/H]
131-137 F7.3 uHz numax [4.78/249] Mean value of numax from all
pipelines from APOKASC2
139-143 F5.3 uHz e_numax [0.05/7.01] Uncertainty on numax
145-150 F6.3 uHz dnu [0.74/19.2] Mean value of dnu from all
pipelines from APOKASC2, with our fdnu
correction
152-156 F5.3 uHz e_dnu [0.004/0.5] Uncertainty on dnu
158-162 F5.3 solMass Mass [0.53/3.4] Asteroseismic mass
164-168 F5.3 solMass e_Mass [0.03/1.1] Uncertainty on Mass
170-174 F5.2 kpc X [-8.26/-5.69] Galactocentric X coordinate
calculated with astropy
176-179 F4.2 kpc Y [0.19/9.18] Galactocentric Y coordinate
calculated with astropy
181-184 F4.2 kpc Z [0.06/2.58] Galactocentric Z coordinate
calculated with astropy
186-190 F5.2 kpc R [7.73/11.09] Galactocentric R coordinate
calculated with astropy
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History:
From electronic version of the journal
(End) Prepared by [AAS], Coralie Fix [CDS], 13-Apr-2021