J/ApJ/881/7 Hot subdwarf stars from LAMOST DR5 & Gaia DR2 (Luo+, 2019)
Hot subdwarf stars observed in Gaia DR2 and LAMOST DR5.
Luo Y., Nemeth P., Deng L., Han Z.
<Astrophys. J., 881, 7-7 (2019)>
=2019ApJ...881....7L 2019ApJ...881....7L (SIMBAD/NED BibCode)
ADC_Keywords: Stars, subdwarf; Effective temperatures; Radial velocities;
Photometry; Optical; Colors; Infrared; Space velocities;
Proper motions; Surveys
Keywords: stars: kinematics and dynamics; subdwarfs; surveys
Abstract:
Combing Gaia DR2 with LAMOST DR5, we spectroscopically identified
924 hot subdwarf stars, among which 32 stars exhibit strong
double-lined composite spectra. We measured the effective temperature
Teff, surface gravity logg, helium abundance y=nHe/nH, and radial
velocities (RVs) of 892 non-composite spectra hot subdwarf stars by
fitting LAMOST observations with TLUSTY/SYNSPEC non-LTE synthetic
spectra. We outlined four different groups in the Teff--logg diagram
with our helium abundance classification scheme and two nearly
parallel sequences in the Teff--log(y) diagram. 3D Galactic space
motions and orbits of 747 hot subdwarf stars with
(GBP-GRP)0<-0.36mag were computed using LAMOST RVs and Gaia
parallaxes and proper motions. Based on the U-V velocity diagram,
Jz-eccentricity diagram, and Galactic orbits, we derived Galactic
population classifications and the fractional distributions of the
four hot subdwarf helium groups in the halo, thin disk, and thick
disk. Comparisons with the predictions of binary population synthesis
calculations suggest that He-rich hot subdwarf stars with log(y)≥0
are from the double helium white dwarfs (HeWDs) merger, He-deficient
hot subdwarf stars with -2.2≤log(y)<-1 from the common envelope
ejection, and He-deficient hot subdwarf stars with log(y)<-2.2 from
the stable Roche lobe overflow channels. The relative number of
He-rich hot subdwarf stars with -1≤log(y)<0 and log(y)≥0 in the halo
is more than twice the prediction of Zhang+ (2017ApJ...835..242Z 2017ApJ...835..242Z) by
more than six times in the thin disk, which implies that the mergers
of HeWDs with low-mass main-sequence stars may not be the main
formation channel for He-rich hot subdwarf stars with -1≤log(y)<0,
especially in younger environments.
Description:
LAMOST DR5 (Cat. V/164) was released to the public in 2017 December
and published more than 9 million spectra. LAMOST DR5 also provided
the effective temperatures, surface gravities, and metallicities of
5,344,058 stars. The LAMOST spectra are similar to the SDSS data with
a resolution R∼1800 and wavelength coverage of 3800-9100Å.
Gaia DR2 (Cat. I/345) was released on 2018 April 25 and provided
high-precision positions, proper motions, and trigonometric parallaxes
as well as three broadband magnitudes for more than 1.3 billion objects.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 236 892 Atmospheric parameters and space positions for 892
non-composite spectra hot subdwarf stars selected
from Gaia DR2 and LAMOST DR5
table3.dat 231 747 Orbital parameters, galactic velocities for 747 hot
subdwarf stars selected from Gaia DR2 and LAMOST DR5
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See also:
VI/65 : Evolutionary models of evolved stars (Dorman+ 1993)
II/246 : 2MASS All-Sky Catalog of Point Sources (Cutri+ 2003)
I/305 : The Guide Star Catalog, Version 2.3.2 (GSC2.3) (STScI, 2006)
I/345 : Gaia DR2 (Gaia Collaboration, 2018)
V/164 : LAMOST DR5 catalogs (Luo+, 2019)
J/ApJ/419/596 : Pop I UV radiation models (Dorman+, 1993)
J/A+A/400/877 : White dwarfs 3D kinematics from SPY project (Pauli+, 2003)
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/A+A/447/173 : 3D-kinematics of WDs from SPY project. II. (Pauli+, 2006)
J/MNRAS/380/1098 : UV-upturn of elliptical galaxies model (Han+, 2007)
J/ApJS/190/1 : A survey of stellar families (Raghavan+, 2010)
J/A+A/530/A28 : Priority targets for the MUCHFUSS project (Geier+, 2011)
J/MNRAS/427/2180 : GALEX survey subdwarf atmospheric parameters (Nemeth+, 2012)
J/A+A/551/A31 : New spectral classification for hot subdwarfs (Drilling+, 2013)
J/MNRAS/448/822 : LAMOST candidate members of star clusters (Xiang+, 2015)
J/A+A/576/A44 : Hot subdwarf binaries from MUCHFUSS (Kupfer+, 2015)
J/A+A/577/A26 : Radial velocities of hot subluminous stars (Geier+, 2015)
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 diagrams (Gaia Collaboration, 2018)
J/A+A/616/A12 : Gaia DR2 sources in GC and dSph (Gaia Collaboration+, 2018)
J/ApJ/868/70 : Hot subdwarf stars from Gaia DR2 and LAMOST DR5 (Lei+, 2018)
J/ApJ/881/135 : Hot subdwarf stars from Gaia DR2 & LAMOST DR5. II. (Lei+, 2019)
J/A+A/621/A38 : Gaia catalogue of hot subluminous stars (Geier+, 2019)
J/MNRAS/485/2562 : Eclipse timing variation of EBs (Hajdu+, 2019)
J/ApJ/898/64 : Hot subdwarf stars from Gaia with LAMOST. II. RVs (Luo+, 2020)
J/ApJS/256/28 : Hot subdwarf stars with Gaia DR2 & LAMOST DR7 data (Luo+, 2021)
http://dr5.lamost.org/ : LAMOST DR5 home page
http://www.cosmos.esa.int/gaia : Gaia home page
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 19 A19 --- LAMOST LAMOST target
21- 45 A25 --- Name Target name in SIMBAD
47- 56 F10.6 deg RAdeg Barycentric Right Ascension (ICRS) at
Epoch=2000
58- 66 F9.6 deg DEdeg [-7/60.5] Barycentric Declination (ICRS) at
Epoch=2000
68- 74 F7.4 mag Gmag [9.17/18.8] Gaia DR2 G-band mean magnitude
76- 82 F7.4 mag GBP-GRP [-0.65/0.46] Gaia DR2 (BP-RP) color
84- 89 F6.4 mag AG [0.02/1.3] Estimate of extinction in G band
91- 97 F7.4 mag E(BP-RP) [-0.031/0.64] Estimate of redenning E(BP-RP)
99- 104 F6.3 mag V-J [-1.7/3.33]? The (V-J) color (1)
106- 111 F6.3 mag J-H [-1.23/0.93]? The (J-H) color (1)
113- 118 F6.4 mas plx [0.03/9.36] Gaia DR2 absolute stellar
parallax
120- 125 F6.4 mas e_plx [0.02/1] Standard error in plx
127- 133 F7.3 mas/yr pmRA [-87.4/82.5] Proper motion in RA
135- 139 F5.3 mas/yr e_pmRA [0.03/1.6] Standard error pmRA
141- 147 F7.3 mas/yr pmDE [-97.6/31.2] Proper motion in DE
149- 153 F5.3 mas/yr e_pmDE [0.03/1.3] Standard error in pmDE
155- 158 I4 km/s RVel [-323/293] Radial velocity from LAMOST
spectra
160- 162 I3 km/s e_RVel [8/115] Standard error in RVel
164- 174 F11.3 1000K Teff [17/5.3e+6] Stellar effective temperature
176- 180 F5.3 1000K e_Teff [0/5.2] Standard error in Teff
182- 185 F4.2 [cm/s2] logg [4.6/6.4] Stellar surface gravity
187- 190 F4.2 [cm/s2] e_logg [0/0.4] Standard error of Stellar surface
gravity
192- 196 F5.2 [Sun] log(y) [-4.3/2.1] Stellar surface He abundance
y=n(He)/n (H)
198- 201 F4.2 [Sun] e_log(y) [0/3] Standard error in log (y)
203- 208 F6.2 kpc X [-26.4/5] Galactic position towards
Galactic center
210- 214 F5.2 kpc e_X [0/11] Standard error in X
216- 220 F5.2 kpc Y [-5.2/12] Galactic position along Galactic
rotation
222- 225 F4.2 kpc e_Y [0/5] Standard error of Y
227- 231 F5.2 kpc Z [-6.5/24] Galactic position towards north
Galactic pole
233- 236 F4.2 kpc e_Z [0/9] Standard error of Z
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Note (1): Optical V magnitudes were acquired from the Guide Star Catalog
(GSC2.3.2; Lasker+ 2008, I/305) and infrared (IR) J and H magnitudes
from the Two Micron All-Sky Survey (Cutri+ 2003, II/246). See Section 2.2.
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Byte-by-byte Description of file: table3.dat
--------------------------------------------------------------------------------
Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 19 A19 --- LAMOST LAMOST target
21- 45 A25 --- Name Target name in SIMBAD
47- 56 F10.6 deg RAdeg Barycentric right ascension (ICRS) at
Epoch=2000
58- 66 F9.6 deg DEdeg [-6.7/60.5] Barycentric declination (ICRS)
at Epoch=2000
68- 73 F6.4 mas plx [0.03/7.1] Gaia DR2 absolute stellar
parallax
75- 80 F6.4 mas e_plx [0.03/0.5] Standard error in plx
82- 88 F7.3 mas/yr pmRA [-87.4/82.5] Proper motion in RA
90- 94 F5.3 mas/yr e_pmRA [0.03/0.6] Standard error pmRA
96- 102 F7.3 mas/yr pmDE [-97.6/31.2] Proper motion in DE
104- 108 F5.3 mas/yr e_pmDE [0.03/0.7] Standard error in pmDE
110- 113 I4 km/s RVel [-323/293] Radial velocity from LAMOST
spectra
115- 117 I3 km/s e_RVel [8/115] Standard error in RVel
119- 122 I4 km.s U [-314/440] Galactic radial velocity positive
toward Galactic center
124- 126 I3 km.s e_U [0/180] Standard error in U
128- 131 I4 km/s V [-813/323] Galactic rotational velocity
along Galactic rotation
133- 135 I3 km/s e_V [1/257] Standard error in V
137- 140 I4 km/s W [-257/445] Galactic velocity toward north
Galactic pole
142- 144 I3 km/s e_W [0/184] Standard error in W
146- 152 F7.2 kpc Rap [6.2/4417.1] Apocenter radius (1)
154- 160 F7.2 kpc e_Rap [0/1673] Standard error in Rap
162- 166 F5.2 kpc Rperi [0.08/34.7] Pericenter radius (1)
168- 172 F5.2 kpc e_Rperi [0.01/14] Standard error in Rperi
174- 181 F8.3 kpc zmax [0.1/1314] Maximum vertical height (1)
183- 188 F6.2 kpc e_zmax [0.01/678] Standard error in zmax
190- 193 F4.2 --- ecc [0/0.98] Eccentricity (1)
195- 198 F4.2 --- e_ecc [0/0.3] Standard error in ecc
200- 208 F9.2 kpc/km/s Jz [-19256/5822] Z-component of angular
momentum
210- 216 F7.2 kpc/km/s e_Jz [4.8/4598] Standard error in Jz
218- 222 F5.2 --- zn [0.01/53.54] Normalised z-extent of the
orbit
224- 228 F5.2 --- e_zn [0/15] Standard error in zn
230- 231 A2 --- Pop Population classification (2)
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Note (1): From the numerical orbit integration.
Note (2): Classification as follows:
H = Halo (107 occurrences)
Tk = thick disk (312 occurrences)
TH = thin disk (328 occurrences)
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 03-Apr-2023