J/ApJ/912/72 High-res. spectroscopy for 26 halo KIC stars (Matsuno+, 2021)
Star formation timescales of the halo populations from asteroseismology and
chemical abundances.
Matsuno T., Aoki W., Casagrande L., Ishigaki M.N., Shi J., Takata M.,
Xiang M., Yong D., Li H., Suda T., Xing Q., Zhao J.
<Astrophys. J., 912, 72 (2021)>
=2021ApJ...912...72M 2021ApJ...912...72M
ADC_Keywords: Stars, halo; Abundances; Radial velocities; Equivalent widths;
Spectra, optical; Stars, giant
Keywords: Halo stars ; Asteroseismology ; Chemical abundances ;
Stellar kinematics ; High resolution spectroscopy ; Stellar ages
Abstract:
We combine asteroseismology, optical high-resolution spectroscopy, and
kinematic analysis for 26 halo red giant branch stars in the Kepler
field in the range of -2.5<[Fe/H]<-0.6. After applying theoretically
motivated corrections to the seismic scaling relations, we obtain an
average mass of 0.97±0.03M☉ for our sample of halo stars.
Although this maps into an age of ∼7Gyr, significantly younger than
independent age estimates of the Milky Way stellar halo, we considered
this apparently young age to be due to the overestimation of stellar
mass in the scaling relations. There is no significant mass dispersion
among lower red giant branch stars (logg>2), which constrains the
relative age dispersion to <18%, corresponding to <2Gyr. The precise
chemical abundances allow us to separate the stars with [Fe/H]>-1.7
into two [Mg/Fe] groups. While the [α/Fe] and [Eu/Mg] ratios are
different between the two subsamples, [s/Eu], where s stands for Ba,
La, Ce, and Nd, does not show a significant difference. These
abundance ratios suggest that the chemical evolution of the low-Mg
population is contributed by Type Ia supernovae, but not by low- to
intermediate-mass asymptotic giant branch stars, providing a
constraint on its star formation timescale as 100Myr<τ<300Myr. We
also do not detect any significant mass difference between the two
[Mg/Fe] groups, thus suggesting that their formation epochs are not
separated by more than 1.5Gyr.
Description:
Targets are selected from the LAMOST DR4 and APOKASC-2 catalogs
(see Section 2.1).
Observations were conducted with the High Dispersion Spectrograph
(HDS) on the Subaru Telescope (from ∼4000 to ∼6800Å). Most of the
targets were observed in 2018 July (R∼80000). A subset of spectra was
taken in 2017 (R∼60000).
All of the targets are in Yu+ (2018, J/ApJS/236/42) catalog, which
provides the results of asteroseismic analysis of red giant stars
using about four years of photometric data in the Kepler field.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 95 28 Observation log
table5.dat 199 470 Line list and measured equivalent widths
table6.dat 61 28 Adopted stellar parameters
table7.dat 42 702 Abundances
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
V/117 : Geneva-Copenhagen Survey of Solar neighbourhood (Holmberg+, 2007)
J/AJ/120/1841 : Abundances & Kinematics of Halo & Disk Stars (Fulbright 2000)
J/ApJ/530/783 : The r-process enriched giant HD 115444 (Westin+, 2000)
J/A+A/416/1117 : Abundances in the early Galaxy (Cayrel+, 2004)
J/ApJ/645/613 : Abundances of HD 221170 (Ivans+, 2006)
J/A+A/505/117 : Abundances of red giants in 15 GCs (Carretta+, 2009)
J/AJ/137/4377 : List of SEGUE plate pairs (Yanny+, 2009)
J/A+A/511/L10 : Abundances and space velocities of 94 stars (Nissen+, 2010)
J/A+A/512/A54 : Teff and Fbol from Infrared Flux Method (Casagrande+, 2010)
J/A+A/523/A17 : Individual stars in Fornax dSph center (Letarte+, 2010)
J/A+A/528/A92 : HERES VI. Gal. chemical evolution of Si & C (Zhang+, 2011)
J/A+A/530/A15 : Abundances of 94 stars (Nissen+, 2011)
J/ApJ/765/L41 : Asteroseismic classification of KIC objects (Stello+, 2013)
J/ApJ/771/67 : Abundances for 97 metal-poor stars. II. (Ishigaki+, 2013)
J/MNRAS/444/392 : Synthetic Stellar Photometry. I. (Casagrande+, 2014)
J/A+A/568/A25 : C and O abundances in stellar populations (Nissen+, 2014)
J/AJ/147/136 : Stars of very low metal abundance. VI. (Roederer+, 2014)
J/ApJS/215/19 : APOKASC catalog of Kepler red giants (Pinsonneault+, 2014)
J/ApJS/220/19 : LAMOST obs. in the Kepler field. I. (De Cat+, 2015)
J/MNRAS/450/397 : Spectroscopic study of RGs in Kepler field (Takeda+, 2015)
J/MNRAS/456/3655 : Masses and ages of red giants (Martig+, 2016)
J/ApJ/817/40 : High-resolution NIR spectra of local giants (Feuillet+, 2016)
J/ApJ/823/114 : The Cannon: a new approach to determine masses (Ness+, 2016)
J/ApJ/827/50 : Kepler faint red giants (Mathur+, 2016)
J/ApJ/832/121 : 4-yr RV survey of red giant in EBs. (Gaulme+, 2016)
J/A+A/585/A102 : Copper abundances in solar neighborhood stars (Yan+, 2016)
J/A+A/589/A115 : Na and Al abundances of 1303 stars (Smiljanic+, 2016)
J/MNRAS/465/3203 : GALAH observational overview (Martell+, 2017)
J/A+A/597/A30 : Seismology and sp. of CoRoGEE red giants (Anders+, 2017)
J/A+A/608/A46 : Constraining cosmic scatter (Reggiani+, 2017)
J/A+A/618/A133 : Non standard s-process in massive rot. stars (Choplin+, 2018)
J/ApJ/865/68 : Abundances for 79 Sun-like stars within 100pc (Bedell+, 2018)
J/ApJ/860/49 : Opt. sp. of young α-rich stars (Matsuno+, 2018)
J/ApJ/868/110 : R-Process Alliance: 1st release in Gal. halo (Sakari+, 2018)
J/ApJS/236/42 : Asteroseismology of ∼16000 Kepler red giants (Yu+, 2018)
J/ApJS/239/32 : APOKASC-2 Kepler evolved stars (Pinsonneault+, 2018)
J/MNRAS/475/5487 : Stellar properties of KIC stars (Silva Aguirre+, 2018)
J/MNRAS/474/2580 : Evolution of neutron-capture elements (Spina+, 2018)
J/MNRAS/475/3633 : Mass and age of red giant branch stars (Wu+, 2018)
J/A+A/624/A19 : GALAH survey, chemodynamical analyse with TGAS (Buder+, 2019)
J/A+A/624/A78 : Masses and ages of 1059 HARPS-GTO stars (Delgado Mena+, 2019)
J/A+A/625/A33 : Radial velocity time series of HD 122563 (Creevey+, 2019)
J/A+A/626/A15 : Sculptor Red Giant Branch stars abundances (Hill+, 2019)
J/A+A/627/A173 : Abundances for 4 metal-poor stars (Valentini+, 2019)
J/A+A/631/A171 : Neutron-capture elements in dwarf gal. (Skuladottir+, 2019)
J/MNRAS/482/965 : Age of the Galactic stellar halo from Gaia WDs (Kilic+, 2019)
J/AJ/157/70 : Sodium-rich stars among metal-poor stars (Pereira+, 2019)
J/MNRAS/493/5195 : Milky Way halo stars ages and kinematics (Das+, 2020)
J/A+A/644/A83 : Jurassic structure (Fernandez-Trincado+, 2020)
J/A+A/645/A85 : Age dissection of the Milky Way discs (Miglio+, 2021)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 3 A3 --- --- [KIC]
5- 12 I8 --- KIC KIC number (G1)
14 A1 --- f_KIC e = Flag on KIC 10992126;
flag added by CDS (1)
16- 26 A11 "Y/M/D" Date Date of observation (UT) (2)
28- 29 I2 d Date2 [11]? Second date of observation if any
31- 34 I4 s Exp [600/5400] Exposure time
36- 40 F5.1 --- S/N [107/265] Signal-to-noise ratio from the
continuum around 5765Å
per 0.024Å pixel
42- 48 F7.2 km/s HRV [-381/-7]? Heliocentric radial velocity
from Subaru/HDS (3)
50- 56 F7.2 km/s HRV-L [-387/-13.5]? LAMOST DR5 radial velocity (4)
58- 62 F5.2 [-] [Fe/H]-L [-2.5/-0.6]? LAMOST DR5 [Fe/H] abundance
64- 70 F7.2 km/s HRV-A [-381/-7]? APOGEE DR16 radial velocity
72- 76 F5.2 [-] [Fe/H]-A [-2.15/-0.51]? APOGEE DR16 [Fe/H] abundance
(4)
78- 84 F7.2 km/s HRV-G [-379.3/-6.6]? Gaia DR2 radial velocity
86- 89 F4.2 km/s e_HRV-G [0.37/4.3]? HRV-G uncertainty
91- 95 F5.2 mag Gmag [10.14/13.21]? Gaia DR2 G-band magnitude
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Note (1): We note that KIC 10992126 was observed but not included in the
analysis, because it turned out to have large uncertainties in the
measured frequencies. See Section 2.2.
Note (2): Observations in 2017 are conducted with R∼60000, while those
in 2018 are with R∼80000.
Note (3): The uncertainty in radial velocity measurements is estimated to be
1km/s considering the stability of the instrument.
Note (4): We adopt measurements from the highest-S/N spectrum of each star for
LAMOST values and those from the combined spectra for APOGEE values.
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Byte-by-byte Description of file: table5.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 8 F8.3 0.1nm lambda [4053.8/6771.1] Wavelength in Angstroms
10- 14 A5 --- Ion Species identifier
16- 20 F5.3 eV ExPot [0/5.11] Excitation potential
22- 27 F6.3 [-] log(gf) [-9.72/0.6] Log oscillator strength
29- 31 A3 --- Syn "syn"=Lines to which spectral
synthesis applied
33- 37 F5.1 10-13m KIC5184073 [5.5/181.2]? KIC5184073 equivalent
width (1)
39- 43 F5.1 10-13m KIC5439372 [3.7/145]? KIC5439372 equivalent width
(1)
45- 49 F5.1 10-13m KIC5446927 [9.8/194.3]? KIC5446927 equivalent
width (1)
51- 55 F5.1 10-13m KIC5698156 [7/193]? KIC5698156 equivalent width
(1)
57- 61 F5.1 10-13m KIC5858947 [2.6/238.6]? KIC5858947 equivalent
width (1)
63- 67 F5.1 10-13m KIC5953450 [4.6/195.6]? KIC5953450 equivalent
width (1)
69- 73 F5.1 10-13m KIC6279038 [2.7/144]? KIC6279038 equivalent width
(1)
75- 79 F5.1 10-13m KIC6520576 [1.7/149.1]? KIC6520576 equivalent
width (1)
81- 85 F5.1 10-13m KIC6611219 [7/201.5]? KIC6611219 equivalent width
(1)
87- 91 F5.1 10-13m KIC7191496 [4/139.1]? KIC7191496 equivalent width
(1)
93- 97 F5.1 10-13m KIC7693833 [1.7/116]? KIC7693833 equivalent width
(1)
99- 103 F5.1 10-13m KIC7948268 [4/163]? KIC7948268 equivalent width
(1)
105- 109 F5.1 10-13m KIC8350894 [7.4/187.4]? KIC8350894 equivalent
width (1)
111- 115 F5.1 10-13m KIC9335536 [5.4/161]? KIC9335536 equivalent width
(1)
117- 121 F5.1 10-13m KIC9339711 [2.8/173.6]? KIC9339711 equivalent
width (1)
123- 127 F5.1 10-13m KIC9583607 [8.6/189]? KIC9583607 equivalent width
(1)
129- 133 F5.1 10-13m KIC9696716 [2.6/146.3]? KIC9696716 equivalent
width (1)
135- 139 F5.1 10-13m KIC10083815 [9.4/191]? KIC10083815 equivalent
width (1)
141- 145 F5.1 10-13m KIC10096113 [8/241.5]? KIC10096113 equivalent
width (1)
147- 151 F5.1 10-13m KIC10328894 [3/140]? KIC10328894 equivalent width
(1)
153- 157 F5.1 10-13m KIC10460723 [3.7/163.7]? KIC10460723 equivalent
width (1)
159- 163 F5.1 10-13m KIC10737052 [3.8/187.6]? KIC10737052 equivalent
width (1)
165- 169 F5.1 10-13m KIC11563791 [4.8/189]? KIC11563791 equivalent
width (1)
171- 175 F5.1 10-13m KIC11566038 [3/167]? KIC11566038 equivalent width
(1)
177- 181 F5.1 10-13m KIC12017985 [2.7/192.3]? KIC12017985 equivalent
width (1)
183- 187 F5.1 10-13m KIC12017985-17 [3.8/144.2]? KIC12017985 equivalent
width from the 2017 observation (1)
189- 193 F5.1 10-13m KIC12253381 [2/152.7]? KIC12253381 equivalent
width (1)
195- 199 F5.1 10-13m HD122563 [0.7/164.2]? HD122563 equivalent
width (1)
--------------------------------------------------------------------------------
Note (1): In units of milli-Angstroms.
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Byte-by-byte Description of file: table6.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- --- [KIC]
5- 12 I8 --- KIC KIC number
14- 16 A3 --- n_KIC ? -17 = 2017 observation for KIC 12017985 (G1)
18- 21 I4 K Teff [4644/5154]? Effective temperature
23- 24 I2 K e_Teff [31/74]? Teff uncertainty
26- 30 F5.3 [cm/s2] logg [1.65/3.15]? Log of surface gravity
32- 36 F5.3 [cm/s2] e_logg [0.004/0.03]? logg uncertainty
38- 42 F5.3 km/s Vt [1.2/1.92]? Microturbulent velocity
44- 48 F5.3 km/s e_Vt [0.03/0.12]? Vt uncertainty
50- 55 F6.3 [Sun] [Fe/H] [-2.5/-0.62]? Log of Fe/H abundance
57- 61 F5.3 [Sun] e_[Fe/H] [0.016/0.06]? [Fe/H] uncertainty
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Byte-by-byte Description of file: table7.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 3 A3 --- --- [KIC]
4- 11 I8 --- KIC KIC number
12- 14 A3 --- n_KIC ? -17 = 2017 observation for KIC 12017985 (G1)
16- 20 A5 --- Ion Species identifier
22- 26 F5.2 [-] [X/H] [-3.52/-0.09]? log number abundance relative
to hydrogen
28- 31 F4.2 [-] e_[X/H] [0/0.17]? Uncertainty in [X/H]
33- 37 F5.2 [-] [X/Fe] [-1.1/0.99]? log number abundance relative
to iron
39- 42 F4.2 [-] e_[X/Fe] [0/0.16]? Uncertainty in [X/Fe]
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Global notes:
Note (G1): KIC 12017985 was observed in both 2017 and 2018 to confirm the
consistency of our analysis. We mainly adopt parameters from the 2018
observation in the figures for this star and flagged the 2017
observation.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 28-Oct-2022