J/ApJS/241/32 OB stars from the LAMOST DR5 spectra (Liu+, 2019)
A catalog of OB stars from LAMOST spectroscopic survey.
Liu Z., Cui W., Liu C., Huang Y., Zhao G., Zhang Bo
<Astrophys. J. Suppl. Ser., 241, 32 (2019)>
=2019ApJS..241...32L 2019ApJS..241...32L
ADC_Keywords: Stars, OB; Spectral types; Spectra, optical; Surveys
Keywords: catalogs ; stars: early-type ; stars: fundamental parameters ; surveys
Abstract:
We present 22901 OB spectra of 16032 stars identified from the Large
Sky Area Multi-Object Fiber Spectroscopic Telescope data release 5
(LAMOST DR5) data set. A larger sample of OB candidates are first
selected from the distributions in the spectral line indices' space.
Then, all 22901 OB spectra are identified by manual inspection. Based
on a subsample validation, we find that the completeness of the OB
spectra reaches about 89±22% for the stars with spectral types
earlier than B7, while around 57±16% B8-B9 stars are identified. The
smaller completeness for late B stars will lead to the difficulty in
discriminating them from A0-A1-type stars. The subclasses of the OB
samples are determined using the software package MKCLASS. With a
careful validation using 646 subsamples, we find that MKCLASS can give
fairly reliable subtypes and luminosity classes for most of the OB
stars. The uncertainty of the spectral subtype is around 1 subtype,
and the uncertainty of the luminosity class is around 1 level.
However, about 40% of the OB stars fail to be assigned to any class by
MKCLASS, and a few spectra are significantly misclassified by MKCLASS.
This is likely because the template spectra of MKCLASS are selected
from nearby stars in the solar neighborhood, while the OB stars in
this work are mostly located in the outer disk and may have lower
metallicities. The rotation of the OB stars may also be responsible
for the misclassifications. Moreover, we find that the spectral and
luminosity classes of the OB stars located in the Galactic latitude
larger than 20° are substantially different with those located in
the latitude smaller than 20°, which may either be due to the
observational selection effect or may hint a different origin of the
high Galactic latitude OB stars.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table3.dat 113 22901 OB stars identified in LAMOST DR5
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See also:
III/195 : Atlas of Optical Spectral Classification OB Stars (Walborn+ 1990)
V/125 : Photometry and Spectroscopy for Luminous Stars (Reed 2005)
III/274 : Galactic O-Star Spectroscopic Survey (GOSSS) (Sota+, 2014)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
V/153 : LAMOST DR4 catalogs (Luo+, 2018)
V/164 : LAMOST DR5 catalogs (Luo+, 2019)
J/A+AS/96/269 : Stellar Models from 0.8 to 120 Msolar (Schaller+, 1992)
J/ApJS/111/377 : Hγ & Hδ absorption features (Worthey+ 1997)
J/AJ/117/981 : Estimation of stellar metal abundance. II. (Beers+, 1999)
J/A+A/437/467 : VLT-FLAMES survey of massive stars (Evans+, 2005)
J/AJ/137/3358 : Speckle interferometry of massive stars (Mason+, 2009)
J/ApJ/718/683 : The edge of the young Galactic disk (Carraro+, 2010)
J/A+A/537/A146 : Stellar models with rotation. 0.8<M<120. (Ekstrom+, 2012)
J/A+A/550/A107 : RV catalogue of O stars in 30 Doradus (Sana+, 2013)
J/ApJS/220/19 : LAMOST obs. in the Kepler field. I. (De Cat+, 2015)
J/AJ/151/13 : LAMOST-Kepler MKCLASS spectral classification (Gray+, 2016)
J/ApJS/226/1 : Carbon stars from LAMOST DR2 data (Ji+, 2016)
J/AJ/153/99 : Gal. outer disk: a field toward Tombaugh 1 (Carraro+, 2017)
J/ApJS/232/16 : Mira stars discovered in LAMOST DR4 (Yao+, 2017)
J/other/RAA/18.68 : Cataclysmic variables from LAMOST DR3 (Han+, 2018)
J/ApJS/234/31 : Carbon stars from LAMOST using machine learning (Li+, 2018)
J/ApJ/855/68 : Massive stars in SDSS-IV/APOGEE SURVEY (Roman-Lopes+, 2018)
J/A+A/616/L15 : Parallaxes and Proper Motions of OB stars (Xu+, 2018)
Byte-by-byte Description of file: table3.dat
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Bytes Format Units Label Explanations
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1- 9 I9 --- ObsID [215136/585213175] Observation identifier
11- 22 F12.8 deg RAdeg Right Ascension in decimal degrees (J2000)
24- 35 F12.8 deg DEdeg Right Ascension in decimal degrees (J2000)
37- 42 F6.2 --- S/N [15/999] Signal to noise ratio at g band
44- 48 I5 --- m_ObsID [1/3073]? ID number of star that was observed
many times
50- 51 I2 --- Nobs [2/24]? Number of exposures of star that
was observed many times
53- 68 A16 --- SSpT SIMBAD spectral type
70- 95 A26 --- MKSpT MKCLASS spectral type (1)
97-103 A7 --- SpT This work spectral/luminosity types
105-113 A9 --- Comm This work "peculiar" spectra identified
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Note (1): We apply MKCLASS, which is an automatic classification package
developed by Gray & Corbally (2014AJ....147...80G 2014AJ....147...80G), to classify the
spectral subtype and luminosity class for the identified OB stars.
MKCLASS assigns question marks to 4922 spectra and 89 "Unclassifiable".
Moreover, MKCLASS cannot converge to a single type but provides
discrepant classifications with different criteria for 4422 spectra.
In these cases, MKCLASS outputs flags like "kB8hA9mK0 Eu", which means
that the K-line determined spectral type is B8, the hydrogen-line
determined type is A9, and the metallic-line classified type is K0.
See Section 4 for further explanations.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 22-Nov-2019