J/MNRAS/512/1710 Study of PRC stars with LAMOST DR7 (He+, 2022)
Identification, mass, and age of primary red clump stars from spectral features
derived with the LAMOST DR7.
He X.-J., Luo A.-L., Chen Y.-Q.
<Mon. Not. R. Astron. Soc. 512, 1710-1721 (2022)>
=2022MNRAS.512.1710H 2022MNRAS.512.1710H (SIMBAD/NED BibCode)
ADC_Keywords: Milky Way ; Stars, late-type ; Spectra, optical ; Spectroscopy ;
Photometry, infrared ; Positional data ; Radial velocities ;
Stars, masses ; Abundances, [Fe/H] ; Effective temperatures ;
Stars, ages ; Stars, distances
Keywords: Methods: data analysis - techniques: spectroscopic - catalogues -
stars: late-type
Abstract:
Although red clump (RC) stars are easy to identify due to their
stability of luminosity and colour, about 20-50 per cent are actually
red giant branch (RGB) stars in the same location on the HR diagram.
In this paper, a sample of 210504 spectra for 184318 primary RC (PRC)
stars from the LAMOST DR7 is identified, which has a purity of higher
than 90 per cent. The RC and the RGB stars are successfully
distinguished through LAMOST spectra (R ∼ 1800 and signal-to-noise
ratio >10) by adopting the XGBoost ensemble learning algorithm, and
the secondary RC stars are also removed. The SHapley Additive
exPlanations (SHAP) value is used to explain the top features that the
XGBoost model selected. The features are around Fe5270, MgH & Mg Ib,
Fe4957, Fe4207, Cr5208, and CN, which can successfully distinguish RGB
and RC stars. The XGBoost is also used to estimate the ages and masses
of PRC stars by training their spectra with Kepler labelled
asteroseismic parameters. The uncertainties of mass and age are 13 and
31 per cent, respectively. Verifying the feature attribution model, we
find that the age-sensitive element XGBoost is consistent with the
literature. Distance of the PRC stars is derived by KS absolute
magnitude calibrated by Gaia EDR3, which has an uncertainty of about 6
per cent and shows the stars mainly located at the Galactic disc. We
also test the XGBoost with R ∼ 250, which is the resolution of the
Chinese Space Station Telescope under construction; it is still
capable of finding sensitive features to distinguish RC and RGB.
Description:
In this paper, we aim to identify high-purity primary RC stars from
the LAMOST DR7 low-resolution spectrum and then extract and analyse
important spectral features related to RGB and RC stars. Spectral
feature extraction is a process of decomposing, recombining, and
selecting spectral data components, which is a key link in spectral
data mining. It not only determines the quality, efficiency, system
complexity, and robustness of subsequent data processing but also
relates to what knowledge can be mined and the interpretability of the
physical meaning of processing results. Finally, the mass, age, and
distance are also provided for the sample stars where the mass and age
are determined from the LAMOST low-resolution spectra, and the
distances are derived from the KS absolute magnitudes.
We select the stars from LAMOST DR7 with specific interval of log g,
Teff and [Fe/H], to widely cover the RC region. Finally, we obtain
819657 stars with signal-to-noise ratio (SNR) higher than 10. XGBoost
is a supervised learning algorithm realized by gradient tree boosting,
which can solve machine-learning problems such as classification and
regression. So as explained in the section 3.1, we use XGBoost to
classify stars spectra yielding to the identification of 210504
spectra belong to 184318 PRC stars. We then compute star masses, ages
et distances using LAMOST DR7 log g, Teff , [Fe/H] and spectrum
value data (i.e see section 4 and 5). We present all estimated data in
the table.dat.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table.dat 382 210504 LAMOST DR7 spectroscopic and physical properties
of 184318 identified primary RC
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See also:
J/ApJS/236/42 : Asteroseismology of ∼16000 Kepler red giants (Yu+, 2018)
VII/233 : 2MASS All-Sky Extended Source Catalog (XSC) (IPAC/UMass, 2003-2006)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
III/284 : APOGEE-2 data from DR16 (Johnsson+, 2020)
V/156 : LAMOST DR7 catalogs (Luo+, 2019)
I/347 : Distances to 1.33 billion stars in Gaia DR2 (Bailer-Jones+, 2018)
I/352 : Distances to 1.47 billion stars in Gaia EDR3 (Bailer-Jones+, 2021)
J/ApJS/245/34 : Abundances for 6 million stars from LAMOST DR5 (Xiang+, 2019)
J/MNRAS/466/3344 : Red-giant stars classification (Elsworth+, 2017)
J/ApJ/858/L7 : Red clump stars selected from LAMOST and APOGEE (Ting+, 2018)
Byte-by-byte Description of file: table.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 40 A40 --- Name Name ID (specid) (1)
42- 138 A97 --- File Spectrum file path (specpath) (2)
140- 148 I9 --- ObsID Observation ID unique for each spectrum
(obsid)
150- 160 F11.7 deg RAdeg Observational right ascension (J2000) (ra)
162- 171 F10.7 deg DEdeg Observational declination (J2000) (dec)
173- 179 F7.2 K Teff Effective temperature (teff)
181- 188 F8.2 K e_Teff ?=-9999 Mean uncertainty of Teff (teff_err)
190- 194 F5.3 [cm/s2] logg Surface gravity (logg)
196- 204 F9.3 [cm/s2] e_logg ?=-9999 Mean uncertainty of logg (logg_err)
206- 211 F6.3 [Sun] [Fe/H] Iron to hydrogen abundance ratio (feh)
213- 221 F9.3 [Sun] e_[Fe/H] ?=-9999 Mean uncertainty of [Fe/H] (feh_err)
223- 229 F7.2 km/s RV Radial velocity (rv)
231- 238 F8.2 km/s e_RV ?=-9999 Mean uncertainty of RV (rv_err)
240- 245 F6.3 mag Jmag ? J band apparent magnitude (Jmag)
247- 251 F5.3 mag e_Jmag ? Mean uncertainty of Jmag (e_Jmag)
253- 258 F6.3 mag Hmag ? H band apparent magnitude (Hmag)
260- 264 F5.3 mag e_Hmag ? Mean uncertainty of Hmag (e_Hmag)
266- 271 F6.3 mag Ksmag ? Ks band apparent magnitude (Kmag)
273- 277 F5.3 mag e_Ksmag ? Mean uncertainty of Ksmag (e_Kmag)
279- 290 F12.9 mag KsMag Ks band absolute magnitude (mk)
292- 302 E11.8 mag e_KsMag Mean uncertainty of KsMag (mk_err)
304- 314 F11.9 Msun M* Star mass estimate (mass)
316- 326 F11.9 Msun e_M* Mean uncertainty of M* (mass_err)
328- 339 F12.9 Gyr Age [] Star age estimate (age)
341- 352 F12.9 Gyr e_Age [] Mean uncertainty of Age (age_err)
354- 366 F13.7 pc D ? Distance estimate (dist)
368- 382 F15.9 pc e_D ? Mean uncertainty of D (dist_err)
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Note (1): Name is made with the observation date Obsdate, the Planid, the Spid,
the Fiberid and the spectrum version v2.9.8 as
SpID = ObsdatePlanidSpidFiberid_v2.9.8 .
Note (2): File is made with /data7/spectra_v2.9.8/Obsdate/Planid/
spec-lmjd-Planid_spSpid-Fiberid.fits .
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History:
From electronic version of the journal
(End) Luc Trabelsi [CDS] 11-Mar-2025