J/ApJ/929/124 Ages, masses & kinematics of GALAH MS turnoff stars (Chen+, 2022)
Ages of main-sequence turnoff stars from the GALAH survey.
Chen X., Ge Z., Chen Y., Bi S., Yu J., Yang W., Ferguson J.W., Wu Y.,
Li Y.
<Astrophys. J., 929, 124 (2022)>
=2022ApJ...929..124C 2022ApJ...929..124C
ADC_Keywords: Abundances; Stars, masses; Stars, ages; Space velocities;
Surveys; Milky Way; Models; Optical
Keywords: Chemical abundances ; Milky Way disk ; Fundamental parameters of stars
Abstract:
Main-sequence turnoff (MSTO) stars are good tracers of Galactic
populations since their ages can be reliably estimated from
atmospheric parameters. Based on the GALAH survey, we use the Yale
rotation evolution code to determine the ages of 2926 MSTO stars with
a mean age uncertainty of ∼10% considering the variation of C and O
abundances. The ages of CO-poor stars are systematically affected by
∼10% due to the C and O abundances, globally shifting to ∼0.5Gyr older
compared to the results using solar metal mixture. Of the stars with
[Fe/H]∼0.3-0.5 or [O/Fe]≤-0.25, many have fractional age differences
of ≥20%, and even reach up to 36%. The age-metallicity relation
appears to possibly indicate the existence of two distinct sequences:
a young sequence of stars with ages mostly <7Gyr, and a relatively
older sequence of stars with ages mostly >7Gyr, overlapping at
5Gyr≤age≤7Gyr. Moreover, the trends of abundances-to-age ratios show
two corresponding sequences, especially in the [O/Fe]-age plane. We
also find that [Y/Mg] is a good chemical clock in disk populations.
The young sequence and the old sequence cannot be separated based on
chemistry or kinematics; therefore, stellar age is an important
parameter to distinguish these two sequences in our sample.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 124 3025 Observational atmospheric parameters, [C/H], [O/H]
and typical errors for temperature, logg, and
[Fe/H] of the sample stars
table6.dat 130 2926 Fundamental and kinematic parameters for the whole
sample determined in this work; updated version
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See also:
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
I/350 : Gaia EDR3 (Gaia Collaboration, 2020)
I/352 : Distances to 1.47 billion stars in Gaia EDR3 (Bailer-Jones+, 2021)
J/A+A/433/185 : Abundance analysis of 102 F and G dwarfs (Bensby+, 2005)
J/MNRAS/367/1329 : Elemental abundances for 176 stars (Reddy+, 2006)
J/A+A/545/A32 : Chemical abundances of 1111 FGK stars (Adibekyan+, 2012)
J/A+A/562/A71 : Abundances of solar neighbourhood dwarfs (Bensby+, 2014)
J/A+A/568/A25 : C and O abundances in stellar populations (Nissen+, 2014)
J/A+A/576/A89 : O abundances from HARPS in F-G stars (Bertran de Lis+, 2015)
J/A+A/608/A112 : Kepler LEGACY stars high-precision abund. (Nissen+, 2017)
J/MNRAS/475/5487 : Stellar properties of KIC stars (Silva Aguirre+, 2018)
J/A+A/630/A104 : Disk and halo stars C, O and Fe abundances (Amarsi+, 2019)
J/A+A/624/A19 : GALAH chemodynamical analyse with TGAS (Buder+, 2019)
J/A+A/624/A78 : Masses & ages of 1059 HARPS-GTO stars (Delgado Mena+, 2019)
J/A+A/621/A112 : Carbon and oxygen in 107 dwarf stars (Pavlenko+, 2019)
J/A+A/639/A127 : Age-chemical-clocks-metallicity relations (Casali+, 2020)
J/ApJ/889/157 : Ages of FGK stars considering C & O abundances (Chen+, 2020)
J/A+A/640/A81 : Abundances of 72 solar-type stars (Nissen+, 2020)
J/MNRAS/506/150 : The GALAH+ Survey DR3 (Buder+, 2021)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- 2MASS GALAH DR3 star identifier
(HHMMSSss+DDMMSSs; J2000) (1)
18- 26 F9.4 K Teff [5600/6875]? Surface effective temperature (1)
28- 38 F11.8 K e_Teff [69/79]? Uncertainty in Teff (1)
40- 48 F9.7 [cm/s2] logg [3.8/4.3]? log, Surface gravity (1)
50- 60 F11.9 [cm/s2] e_logg [0.06/0.3]? Uncertainty in logg (1)
62- 73 E12.4 [-] FeH [-0.6/0.6] Metallicity, [Fe/H] (1)
75- 85 F11.9 [-] e_FeH [0.04/0.05]? Uncertainty in Fe/H (1)
87- 98 E12.4 [-] [C/H] [-0.5/0.6] Carbon abundance (1)
100-111 E12.4 [-] [O/H] [-1.2/0.7]? Oxygen abundance (1)
113-124 E12.4 [-] [a/Fe] [-0.7/0.6] α element abundance,
relative to Fe (1)
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Note (1): All values taken from the GALAH DR3 catalog,
Buder+ (2021, J/MNRAS/506/150)
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Byte-by-byte Description of file: table6.dat
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Bytes Format Units Label Explanations
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1- 16 A16 --- 2MASS GALAH DR3 star identifier as in Table 1 (1)
18- 23 F6.4 Msun Mstar [0.8/1.5] Stellar mass, derived with CO-mixtures
25- 33 E9.4 Msun e_Mstar [-0.1/0] Lower uncertainty for Mstar
35- 40 F6.4 Msun E_Mstar [0/0.1] Upper uncertainty for Mstar
42- 48 F7.4 Gyr AgeCO [1.2/13.5] Age, derived with CO-mixtures
50- 56 F7.4 Gyr e_AgeCO [-1.4/-0.007] Lower uncertainty for AgeCO
58- 63 F6.4 Gyr E_AgeCO [0.006/2.1] Upper uncertainty for AgeCO
65- 71 F7.4 Gyr Age [1.2/13.5] Age, derived with GS98 solar-mixture
or alpha-enhanced mixtures
73- 79 F7.4 Gyr e_Age [-1.5/-0.002] Lower uncertainty for Age
81- 86 F6.4 Gyr E_Age [0.006/2.1] Upper uncertainty for Age
88-101 F14.9 km/s U [-141/105]? LSR U space motion
103-116 F14.9 km/s V [-132/51]? LSR V space motion
118-130 F13.9 km/s W [-80/69]? LSR W space motion
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Note (1): ID "12253460-2737473" was a misprint for "12253460-2735247";
corrected at CDS.
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History:
From electronic version of the journal
* 12-Apr-2024: Insert into VizieR
* 19-Apr-2024: misprint corrected in Table 6; CDS acknowledges the author
Acknowledgements:
Zhishuai Ge [gezhishuai at mail.bnu.edu.cn]
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 07-Mar-2024