J/A+A/685/A66 Asteroseismically calibrated ages for APOGEE DR17 (Boulet, 2024)
A catalogue of asteroseismically calibrated ages for APOGEE DR17.
The predictions of a CatBoost machine learning model based on the [Mg/Ce]
chemical clock and other stellar parameters.
Boulet T.
<Astron. Astrophys. 685, A66 (2024)>
=2024A&A...685A..66B 2024A&A...685A..66B (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Stars, giant ; Stars, ages ; Asteroseismology
Keywords: asteroseismology - catalogs - Galaxy: abundances - Galaxy: evolution -
Galaxy: formation
Abstract:
The formation history and evolution of the Milky Way through
cosmological time is a complex field of research requiring the
sampling of highly accurate stellar ages for all Galaxy components.
Such highly reliable ages are starting to become available thanks to
the synergy of asteroseismology, spectroscopy, stellar modelling and
machine learning analysis in the era of all-sky astronomical surveys.
The goal is to provide an accurate list of ages for the Main Red Star
Sample of the APOGEE DR17 catalogue. In order to reach this goal, ages
obtained under asteroseismic constraints are used to train a model of
machine learning. Since the main objective is to obtain reliable age
predictions without needing asteroseismic parameters, the optimal
choice of stellar non-asteroseismic parameters was investigated to
obtain the best performances on the test set. The stellar parameters
Teff, L, the abundances of [CI/N],[Mg/Ce], [alpha/Fe], as the U(LSR)
velocity and the vertical height from the Galactic plane Z were used
to predict ages with a Categorical Gradient Boost Decision Trees
model. The model was trained on two merged samples of the TESS
Southern Continuous Viewing Zone and the Second APOKASC catalogue to
avoid a data shift and improve the reliability of the predictions.
Finally, the model was tested on an independent data set of the K2
Galactic Archaeology Program. A model with a median fractional age
error of 20.8% is obtained. Its prediction variance between the
validation and the training set is 4.77%. For stars older than 3Gyr,
the median fractional error in age ranges from 7% to 23%. For stars
with ages ranging from 1 to 3Gyr, the median fractional error in age
ranges from 26% to 28%. For stars younger than 1 Gyr the median
fractional error is 43%. The optimised model applies to 125,445 stars
from the Main Red Star Sample of the APOGEE DR17 catalogue. The
analysis of the ages confirms previous findings regarding the flaring
of the young Galactic disc towards its outer regions. Additionally, an
age gradient is found among the youngest stars within the Galactic
plane. Finally, two groups of a few metal-poor ([Fe/H]←1dex) young
stars (Age<2Gyr) with similar peculiar chemical abundances and Halo
kinematics are identified. They are likely the outcome of the
predicted third and latest episode of gas infall in the solar vicinity
(around 2.7Gyr ago).
A catalogue of asteroseismically calibrated ages for 125445 red
giants from the APOGEE DR17 catalogue is made available to the
community. The analysis of the associated stellar parameters
corroborates the predictions of different literature models.
Description:
The catalogue is made of red giant stars in the APOGEE DR17 field.
These stars span a constrained range of stellar parameters and were
selected because of their reliable abundances and luminosities.
File Summary:
--------------------------------------------------------------------------------
FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
age_cat.dat 399 125445 *Stellar ages obtained using the CatBoostRegressor
model
--------------------------------------------------------------------------------
Note on age_cat.dat: listing other relevant stellar parameters, for the 125445
red giants of the catalogue. A partial version of this table can be found in
Table 6 of the associated article.
--------------------------------------------------------------------------------
See also:
I/355 : Gaia DR3 Part 1. Main source (Gaia Collaboration, 2022)
III/286 : APOGEE-2 DR17 final allStar catalog (Abdurro'uf+, 2022)
Byte-by-byte Description of file: age_cat.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 10 F10.6 deg RAdeg Right Ascension (ICRS) at Ep=2016.0 (RA)
12- 21 E10.6 deg DEdeg Declination (ICRS) at Ep=2016.0 (DEC)
23- 28 F6.4 deg e_RAdeg Error in Right Ascension (e_RAdeg)
30- 35 F6.4 deg e_DEdeg Error in Declination (e_DEdeg)
37- 51 F15.11 deg RAJdeg Right Ascension (J2000) (RAJ2000)
53- 67 E15.11 deg DEJdeg Declination (J2000) (DEJ2000)
69- 76 A8 --- --- [Gaia DR3]
78- 96 I19 --- GaiaDR3 Identifier for the GAIA Data Release 3
(GAIA DR3)
98-102 F5.2 Gyr Age The age computed with the CatBoostRegressor
model (Age)
104-107 F4.2 Gyr e_Age Error in age due to the CatBoostRegressor
model (Age_ERR)
109-113 F5.2 [-] [Fe/H] APOGEE DR17 Iron ratio in dex (FE_H)
115-118 F4.2 [-] e_[Fe/H] APOGEE DR17 Error in Iron ratio in dex
(FEHERR)
120-123 I4 K Teff APOGEE DR17 Effective temperature (TEFF)
125-126 I2 K e_Teff APOGEE DR17 Error in Effective temperature
(TEFF_ERR)
128-131 F4.2 [cm/s2] logg APOGEE DR17 Surface gravity (LOGG)
133-136 F4.2 [cm/s2] e_logg APOGEE DR17 Error in Surface gravity
(LOGG_ERR)
138-143 F6.3 mag Ksmag APOGEE DR17 Ks-band magnitude (Ks)
145-149 F5.3 mag e_Ksmag APOGEE DR17 Error Ks-band magnitude
(Ks_ERR)
151-154 F4.2 mag E(B-V) Reddening ) parameter computed with the
MW 3D Dust maps (E(B-V))
156-160 F5.3 mag BCKs Bolometric correction for the Ks band
computed with E(B-V) (BC_Ks)
162-167 F6.2 [Lsun] LBol Bolometric luminosity computed with BC_Ks
(L_Bol)
169-174 F6.2 [Lsun] e_LBol Error in Bolometric luminosity (L_Bol )
176-180 F5.2 [-] [alpha/Fe] APOGEE DR17 Alpha (Mg+Si) to Iron ratio
in dex (ALPHA_FE)
182-185 F4.2 [-] e_[alpha/Fe] APOGEE DR17 Error in Alpha (Mg+Si) to Iron
ratio in dex (ALPHAFEERR)
187-191 F5.2 [-] [CI/N] APOGEE DR17 atomic Carbon to Nitrogen
ratio in dex (CI_N)
193-196 F4.2 [-] e_[CI/N] APOGEE DR17 Error in atomic Carbon to
Nitrogen ratio in dex (CINERR)
198-202 F5.2 [-] [Mg/Ce] APOGEE DR17 Magnesium to Cerium ratio
(MG_CE) in dex
204-207 F4.2 [-] e_[Mg/Ce] APOGEE DR17 Error in Magnesium to Cerium
ratio in dex (MGCEERR)
209-215 F7.2 km/s U(LSR) U velocity in the Local Standard of Rest
(U(LSR))
217-222 F6.2 km/s e_U(LSR) Error in U velocity in the Local Standard
of Rest (U_ERR)
224-230 F7.2 km/s V(LSR) V velocity in the Local Standard of Rest
(V(LSR))
232-237 F6.2 km/s e_V(LSR) Error in V velocity in the Local Standard
of Rest (V_ERR)
239-245 F7.2 km/s W(LSR) W velocity in the Local Standard of Rest
(W_LSR)
247-252 F6.2 km/s e_W(LSR) Error in W velocity in the Local Standard
of Rest (W_ERR)
254-268 F15.11 deg GLON Galactic longitude (GLON)
270-284 F15.11 deg GLAT Galactic latitude (GLAT)
286-291 F6.4 mas Plx Gaia DR3 Parallax (Plx)
293-298 F6.4 mas e_Plx Error in Gaia DR3 Parallax (Plx_ERR)
300-318 F19.16 kpc X Galactocentric X coordinate (X)
320-338 F19.16 kpc Y Galactocentric Y coordinate (Y)
340-358 F19.16 kpc Z Galactocentric Z coordinate (Z)
360-365 F6.3 kpc rperi Stellar orbit pericenter distance,
computed with Galpy (rperi)
367-373 F7.3 kpc rap Stellar orbit apocenter distance,
computed with Galpy (rap)
375-379 F5.3 --- e Eccentricity of the orbit, computed with
Galpy (e)
381-387 F7.3 kpc zmax Maximum vertical distance from the
Galactic plane, computed with Galpy (zmax)
389-397 F9.3 kpc.km/s Lz Vertical Angular momentum, computed with
Galpy (Lz)
399 I1 --- FlagYMP [0/2] Flag for Young Metal-Poor (YMG)
stars (Flag_YMP) (1)
--------------------------------------------------------------------------------
Note (1): Flag for Young Metal-Poor (YMG) stars as follows:
0 = the star is not young and metal-poor
1 = the star belong to the first group
2 = the star belong to the second group
--------------------------------------------------------------------------------
Acknowledgements:
Thibault Boulet, thibault.boulet(at)astro.up.pt
(End) Patricia Vannier [CDS] 30-Dec-2023