J/ApJ/881/135 Hot subdwarf stars from Gaia DR2 and LAMOST DR5. II. (Lei+, 2019)
New hot subdwarf stars identified in Gaia DR2 with LAMOST DR5 spectra. II.
Lei Z., Zhao J., Nemeth P., Zhao G.
<Astrophys. J., 881, 135 (2019)>
=2019ApJ...881..135L 2019ApJ...881..135L
ADC_Keywords: Stars, subdwarf; Effective temperatures; Spectral types; Surveys
Keywords: subdwarfs ; surveys
Abstract:
Three hundred and eighty eight hot subdwarf stars have been identified
by using the Hertzsprung-Russell (HR) diagram built from the second
data release of the Gaia mission. By analyzing their observed Large
Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) spectra,
we characterized 186 sdB, 73 He-sdOB, 65 sdOB, 45 sdO, 12 He-sdO, and
7 He-sdB stars. The atmospheric parameters of these stars (e.g., Teff,
logg, log(nHe/nH)) are obtained by fitting the hydrogen (H) and helium
(He) line profiles with synthetic spectra calculated from non-local
thermodynamic equilibrium model atmospheres. Among these stars, we
have 135 new identified hot subdwarfs which have not been cataloged
before. Although 253 stars appear in the catalog by
Geier+ (2017, J/A+A/600/A50), only 91 of them have atmospheric
parameters. Together with the 294 hot subdwarf stars found by
Lei+ (Paper I, 2018, J/ApJ/868/70), we identified 682 hot subdwarf
stars in total by using the Gaia HR-diagram and LAMOST spectra. These
results demonstrate the efficiency of our method to combine large
surveys to search for hot subdwarf stars. We found a distinct gap in
our He-sdOB stars based on their He abundance, which is also presented
in extreme horizontal branch (EHB) stars of the globular cluster
ω Cen. The number fraction of the sample size for the two
subgroups is very different between the two counterparts. However, the
distinct gap between the H-sdB stars and He-sdOB stars in ω Cen
is not visible in our sample. More interestingly, the He-sdB
population with the highest He abundance in our sample is completely
missing in ω Cen. The discrepancy between our field hot subdwarf
stars and the EHB stars in ω Cen indicate different origins for
the two counterparts.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table1.dat 111 388 Information on the 388 hot subdwarf stars
identified in this study
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See also:
VI/65 : Evolutionary models of evolved stars (Dorman+ 1993)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
V/153 : LAMOST DR4 catalogs (Luo+, 2018)
V/164 : LAMOST DR5 catalogs (Luo+, 2019)
J/ApJ/419/596 : Pop I UV radiation models (Dorman+, 1993)
J/ApJ/562/368 : UV photometry in NGC 2808 (Brown+, 2001)
J/A+A/400/939 : Stellar parameters of 115 HQS sdB stars (Edelmann+, 2003)
J/A+A/430/223 : Parameters of cool companions of sdB stars (Lisker+, 2005)
J/MNRAS/409/582 : Helium-rich subluminous B stars abundances (Naslim+, 2010)
J/A+A/526/A136 : Hot HB stars in ω Cen (Moehler+, 2011)
J/A+A/547/A109 : Parameters of HB stars in ω Cen (Moni Bidin+, 2012)
J/MNRAS/427/2180 : GALEX survey subdwarf atmospheric parameters (Nemeth+, 2012)
J/A+A/551/A31 : New spectral classif. for hot subdwarfs (Drilling+, 2013)
J/A+A/565/A100 : NGC 288 hot HB stars abundances (Moehler+, 2014)
J/MNRAS/446/4078 : New white dwarf stars in SDSS DR10 (Kepler+, 2015)
J/A+A/576/A44 : Hot subdwarf binaries from MUCHFUSS (Kupfer+, 2015)
J/MNRAS/455/3413 : New WD and subdwarf stars in SDSS DR12 (Kepler+, 2016)
J/ApJ/818/202 : Hot subdwarf stars in LAMOST DR1 (Luo+, 2016)
J/A+A/600/A50 : Catalog of hot subdwarf stars (Geier+, 2017)
J/A+A/616/A10 : 46 open clusters GaiaDR2 HR diag. (Gaia Collaboration, 2018)
J/A+A/618/A15 : Parameters of EHB stars in ω Cen (Latour+, 2018)
J/ApJ/868/70 : Hot subdwarf stars from Gaia DR2 and LAMOST DR5 (Lei+, 2018)
J/A+A/621/A38 : Gaia catalog of hot subluminous stars (Geier+, 2019)
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
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1- 10 F10.6 deg RAdeg LAMOST Right Ascension (J2000)
12- 12 A1 --- G17 [*] Listed (*) in hot subdwarf catalog of
Geier+ (2017, J/A+A/600/A50)
14- 22 F9.6 deg DEdeg [-7.2/60.5] LAMOST Declination (J2000)
24- 24 A1 --- N12 [d] Listed (d) in
Nemeth+ (2012, J/MNRAS/427/2180)
26- 34 I9 --- obsID LAMOST DR5 observation identifier
36- 37 A2 --- L16 [dd ] Listed (dd)
in Luo+ (2016, J/ApJ/818/202)
39- 57 I19 --- Gaia Gaia DR2 source identifier
59- 64 I6 K Teff [22580/105770] Effective Temperature
from XTgrid fit
66- 70 I5 K e_Teff [20/29720] Uncertainty in Teff
72- 75 F4.2 [cm/s2] logg [5/7.1] Surface gravity from XTgrid fit
77- 80 F4.2 [cm/s2] e_logg [0.01/0.5] Uncertainty in logg
82- 86 F5.2 [-] log(nHe/nH) [-3.43/3.65] log, nHe/nH from XTgrid fit
88- 91 F4.2 [-] e_log(nHe/nH) [0.02/0.8]? Uncertainty in log(nHe/nH)
93- 93 A1 --- l_log(nHe/nH) Upper limit flag for log(nHe/nH)
95- 97 I3 --- SNRU [10/160] Signal-to-Noise ratio
in the u band
99-103 F5.2 mag Gmag [10.64/18.25] Gaia DR2 G magnitude
105-111 A7 --- SpT Spectral Classification
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History:
From electronic version of the journal
References:
Lei et al. Paper I. 2018ApJ...868...70L 2018ApJ...868...70L Cat. J/ApJ/868/70
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 26-Jan-2021