J/ApJ/931/133 S-type stars from LAMOST MRS DR9 with Gaia DR2 data (Chen+, 2022)
S-type stars discovered in Medium-Resolution Spectra of LAMOST DR9.
Chen J., Luo A.-L., Li Y.-B., Chen X.-L., Wang R., Li S., Du B., Ma X.-X.
<Astrophys. J., 931, 133 (2022)>
=2022ApJ...931..133C 2022ApJ...931..133C
ADC_Keywords: Stars, S; Spectra, optical; Surveys; Photometry, infrared;
Abundances; Colors; Parallaxes, trigonometric;
Magnitudes, absolute
Keywords: S stars
Abstract:
In this paper, we report on 606 S-type stars identified from Data
Release 9 of the LAMOST medium-resolution spectroscopic (MRS) survey;
539 of them are reported for the first time. The discovery of these
stars is a three-step process, i.e., selecting with ZrO-band indices
greater than 0.25, excluding non-S-type stars with the iterative
Support Vector Machine method, and finally retaining stars with
absolute bolometric magnitude larger than -7.1. The 606 stars are
consistent with the distribution of known S-type stars in the color-
magnitude diagram. We estimated the C/Os using the [C/Fe] and [O/Fe]
provided by APOGEE and the MARCS model for S-type stars, respectively,
and the results of the two methods show that the C/Os of all stars are
larger than 0.5. Both the locations on the color-magnitude diagram and
C/Os further verify the nature of our S-type sample. Investigating the
effect of TiO and atmospheric parameters on ZrO with the sample, we
found that log g has a more significant impact on ZrO than Teff and
[Fe/H], and both TiO and logg may negatively correlate with ZrO.
According to the criterion of Tian+ (2020, J/ApJS/249/22), a total of
238 binary candidates were found by the zero-point-calibrated radial
velocities from the officially released catalog of LAMOST MRS and the
catalog of Zhang+ 2021, J/ApJS/256/14.
Description:
In 2018 October, LAMOST, a 4m Schmidt telescope, started the phase II
survey, which contains both low- and medium-resolution spectroscopic
surveys. In 2020 June, LAMOST delivered its eighth data release (DR8),
which provides 17,628,024 single exposure and 4,728,861 coadded MRS.
From September 2020 to June 2021, LAMOST collected an additional
6,054,085 single-exposure spectra and 1,724,868 combined spectra (DR9).
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table7.dat 176 613 The S-type star catalog constructed in this work
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See also:
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
V/156 : LAMOST DR7 catalogs (Luo+, 2019)
III/284 : APOGEE-2 data from DR16 (Johnsson+, 2020)
J/MNRAS/400/1413 : Near-IR spectra of extremely red AGB stars (Wright+, 2009)
J/AJ/142/103 : Cool evolved stars in SAGE-SMC and SAGE-LMC (Boyer+, 2011)
J/ApJ/727/53 : Red supergiant stars in the LMC. I. (Yang+, 2011)
J/ApJ/831/20 : C/O and Mg/Si for solar neighborhood's stars (Brewer+, 2016)
J/A+A/601/A10 : MARCS model atmospheres for S stars (Van Eck+, 2017)
J/AJ/156/90 : APOGEE radial velocity standard stars (Huang+, 2018)
J/ApJ/858/L7 : Red clump stars selected from LAMOST & APOGEE (Ting+, 2018)
J/MNRAS/475/3633 : Mass and age of red giant branch stars (Wu+, 2018)
J/AJ/158/22 : IR study of intrinsic & extrinsic S-type stars (Chen+, 2019)
J/A+A/629/A91 : A source catalog for the SMC (Yang+, 2019)
J/ApJS/249/22 : Radial velocity variable stars from LAMOST DR4 (Tian+, 2020)
J/ApJS/256/14 : RVs from LAMOST MRS DR7 stellar spectra (Zhang+, 2021)
J/ApJS/256/43 : O-rich and C-rich AGB stars in our Galaxy (Suh, 2021)
J/ApJS/267/5 : S-type stars from LAMOST MRS DR10 spectra (Chen+, 2023)
Byte-by-byte Description of file: table7.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- LAMOST LAMOST DR9 designation (JHHMMSS.ss+DDMMSS.s)
21- 31 F11.7 deg RAdeg Right Ascension (J2000)
33- 42 F10.7 deg DEdeg [-8/77] Declination (J2000)
44- 49 F6.2 --- SNR [5.4/715] Median Signal-to-Noise (1)
51- 63 A13 --- Type Main object type from SIMBAD
65- 74 A10 --- SpType Spectral type from SIMBAD
76- 80 F5.2 --- TiO [-0.25/0.54] TiO index value (2)
82- 85 F4.2 --- ZrO [0.25/0.71] ZrO index value (2)
87- 90 A4 --- Bin Binary candidate class (3)
92- 95 F4.2 --- C/O(A) [0/0.96]? Carbon to oxygen abundance ratio
from APOGEE DR16 estimated by the [C/Fe]
and [O/Fe]
97-100 F4.2 --- C/O(M) [0.5/0.99]? Carbon to oxygen abundance ratio
from MARCS S-type model
102-107 F6.2 mag MBol [-11.1/1.1] Absolute bolometric magnitude
109-114 F6.3 mas plx [0.003/2.31] Gaia DR2 parallax
116-120 F5.3 mas e_plx [0.02/0.6] Uncertainty in plx
122-126 F5.2 mag Gmag [6.4/14.7] Mean Gaia DR2 G band magnitude
128-132 F5.2 mag Bpmag [7.4/17.4] Mean Gaia DR2 Blue band magnitude
134-138 F5.2 mag Rpmag [5.5/13.3] Mean Gaia DR2 Red band magnitude
140-143 F4.2 mag Bp-Rp [1.87/7] Mean Gaia DR2 (Bp-Rp) color index
145-149 F5.2 mag Jmag [3.3/11.5] 2MASS J band magnitude
151-154 F4.2 mag e_Jmag [0.02/0.4] Uncertainty in Jmag
156-160 F5.2 mag Hmag [1.9/10.7] 2MASS H band magnitude
162-165 F4.2 mag e_Hmag [0.01/0.3] Uncertainty in Hmag
167-171 F5.2 mag Ksmag [1/10.4]? 2MASS Ks band magnitude
173-176 F4.2 mag e_Ksmag [0/9.99]? Uncertainty in Ksmag
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Note (1): The median value of all pixel single-to-noises (S/Ns) in the single
exposure red band spectrum, which is the highest S/N of multiple
epoch for one star.
Note (2): Obtained from the red band spectrum with the highest S/N,
discussed in Section 4.
Note (3): Binary candidate class as follows:
E = extrinsic S-type binary candidate using both RVredLAMOST
(RV comparison of red-band spectra from the LAMOST MRS) and
RVredZhang (RV comparison of red-band spectra from
Zhang+ 2021, J/ApJS/256/14); 128 occurrences
E_L = extrinsic S-type binary candidate using only RVredLAMOST;
73 occurrences
E_Z = extrinsic S-type binary candidate using only RVredZhang;
39 occurrences
See Section 4.2.
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History:
From electronic version of the journal
References:
Chen et al. Paper II. 2023ApJS..267....5C 2023ApJS..267....5C Cat. J/ApJS/267/5
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 16-Aug-2023