J/A+A/690/A107 [Y/Mg] chemical clock in the Galactic disk (Shejeelammal+, 2024)
The [Y/Mg] chemical clock in the Galactic disk. The influence of metallicity
and the Galactic population in the solar neighbourhood.
Shejeelammal J., Melendez J., Rathsam A., Martos G.
<Astron. Astrophys. 690, A107 (2024)>
=2024A&A...690A.107S 2024A&A...690A.107S (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Stars, nearby ; Stars, ages ; Abundances
Keywords: techniques: spectroscopic - stars: abundances - stars: solar-type -
Galaxy: disk - solar neighborhood
Abstract:
Stellar ages are an important parameter in studies of the chemical
evolution of the Galaxy. To better estimate these ages, various
methods complementary to the conventional isochrone fitting method
have been implemented in the past decade. Several recent studies have
established the existence of a relationship between chemical clocks
and stellar ages. The [Y/Mg] clock is a promising technique, but there
are still several open questions, such as its validity for metal-poor
stars and differences between the thin and thick disk populations. Our
aim is to study the relationship between the [Y/Mg] chemical clock and
stellar ages for a sample of solar-type disk stars and to provide the
empirical dating relation(s) for the stellar age determination from
their precise chemical abundances. We also studied the effect of
metallicity and populations on this chemical clock. We derived precise
stellar atmospheric parameters as well as the elemental abundances of
Mg and Y through line-by-line differential spectroscopic analysis for
a sample of 48 metal-poor solar-type stars based on high-quality,
high-resolution ESO/HARPS spectra. From high-precision Gaia
astrometric data, stellar masses and ages were estimated through
isochrone fitting using Yonsei-Yale isochrones. A joint analysis of
our sample, together with a sample of 185 solar twins and analogues
from our previous works, was performed to calibrate the [Y/Mg]
chemical clock in the Galactic disk for -0.71≤[Fe/H]<+0.34. Open
clusters and stars with asteroseismic ages were used to validate our
relations. Two different populations are clearly seen in the
[Mg/Fe]-[Fe/H] plane: the thick and thin disks. Thick disk stars show
an age-metallicity relation, whereas the thin disk shows a flatter
age-metallicity distribution. We find a strong, metallicity-dependent
anti-correlation between the [Y/Mg] ratio and the stellar ages of our
sample. For the first time in the literature, we report similar
correlations for thin and thick disk stars. We find that the [Y/Mg]
relation(s) found here for solar-type stars in a wide metallicity
range are compatible with those found for solar twins in the
literature. Our relation provides high accuracy and precision (0.45
and 0.99 Gyr, respectively) comparable with the best accuracy achieved
for solar twins to date.
Description:
We present the stellar atmospheric parameters, mass, age, and
elemental abundance ratios of the sample of 233 solar-type stars
analysed in this study.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
tablea1.dat 121 48 Stellar atmospheric parameters, mass, age, and
elemental abundance ratios of the sample
analysed in this study
tablea2.dat 121 185 Stellar atmospheric parameters, mass, age, and
elemental abundance ratios of the
solar twins and analogues
(corrected version, 04/02/2025)
--------------------------------------------------------------------------------
Byte-by-byte Description of file: tablea1.dat tablea2.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 A9 --- Name Star Name
11- 16 I6 --- HIP Star HIP identifier
18- 21 I4 K Teff Effective temperature
23- 24 I2 K e_Teff Error in temperature
26- 29 F4.2 [cm/s2] logg Surface gravity
31- 34 F4.2 [cm/s2] e_logg Error in logg
36- 41 F6.3 [-] [Fe/H] metallicity
43- 47 F5.3 [-] e_[Fe/H] Error in metallicity
49- 52 F4.2 km/s Vt Microturbulent velocity
54- 57 F4.2 km/s e_Vt Error in microturbulent velocity
59- 63 F5.2 Gyr Age Stellar age
65- 68 F4.2 Gyr e_Age Lower error in age
70- 73 F4.2 Gyr E_Age Upper error in age
75- 78 F4.2 Msun Mass Stellar mass in solar unit
80- 83 F4.2 Msun e_Mass Lower error in mass
85- 88 F4.2 Msun E_Mass Upper error in mass
90- 94 F5.2 [-] [Mg/Fe] Mg abundance relative to Fe
96- 99 F4.2 [-] e_[Mg/Fe] Error in [Mg/Fe]
101-105 F5.2 [-] [Y/Fe] Y abundance relative to Fe
107-110 F4.2 [-] e_[Y/Fe] Error in [Y/Fe]
112-116 F5.2 [-] [Y/Mg] Y abundance relative to Mg
118-121 F4.2 [-] e_[Y/Mg] Error in [Y/Mg]
--------------------------------------------------------------------------------
Acknowledgements:
Jameela Shejeelammal, shejeela(at)usp.br
History:
01-Oct-2024: on-line version
04-Feb-2025: table A2 corrected
(End) Patricia Vannier [CDS] 19-Sep-2024