J/ApJS/257/54 Early-type star param. from LAMOST LRS & MRS (Guo+, 2021)
The early-type stars from the LAMOST survey: atmospheric parameters.
Guo Y., Zhang B., Liu C., Li J., Li J., Wang L., Liu Z.,
Hou Y.-H., Han Z., Chen X.
<Astrophys. J. Suppl. Ser., 257, 54 (2021)>
=2021ApJS..257...54G 2021ApJS..257...54G
ADC_Keywords: Abundances; Effective temperatures; Stars, early-type; Surveys;
Spectra, optical
Keywords: Early-type stars ; Astronomy data analysis ; Surveys ; Catalogs
Abstract:
Massive stars play key roles in many astrophysical processes. Deriving
the atmospheric parameters of massive stars is important to
understanding their physical properties, and thus the atmospheric
parameters are key inputs to trace the evolution of massive stars.
Here we report our work on adopting the data-driven technique called
stellar label machine (SLAM) with the nonlocal thermal equilibrium
TLUSTY synthetic spectra as the training data set to estimate the
stellar parameters of Large Sky Area Multi-Object Fiber Spectroscopic
Telescope (LAMOST) optical spectra for early-type stars. We apply two
consistency tests to verify this machine-learning method and compare
stellar labels given by SLAM with the labels in the literature for
several objects having high-resolution spectra. We provide the stellar
labels of effective temperature (Teff), surface gravity (logg),
metallicity ([M/H]), and projected rotational velocity (vsini) for
3931 and 578 early-type stars from the LAMOST low-resolution survey
(LRS) and medium-resolution survey (MRS), respectively. To estimate
the average statistical uncertainties of our results, we calculated
the standard deviation between the predicted stellar label and the
prelabeled published values from the high-resolution spectra. The
uncertainties of the four parameters are σ(Teff)=2185K,
σ(logg)=0.29dex, and σ(vsini)=11km/s for MRS, and
σ(Teff)=1642K, σ(logg)=0.25dex, and σ(vsini)=42km/s
for LRS spectra, respectively. We note that the parameters of Teff,
logg, and [M/H] can be better constrained using LRS spectra than using
MRS spectra, most likely due to their broad wavelength coverage, while
vsini is constrained better by MRS spectra than by LRS spectra,
probably due to the relatively accurate line profiles of MRS spectra.
Description:
LAMOST is a 4m quasi-meridian reflecting Schmidt telescope located at
the Xinlong station of the National Astronomical Observatory. Both a
low-resolution spectrograph (LRS; R∼1800 with wavelength coverage
of 3690∼9100Å) and a medium-resolution spectrograph (MRS; R∼7500
blue arm: 4950∼5350å and red arm 6300∼6800Å) were installed on
the telescope.
LAMOST finished the first observing campaign from 2011 to 2018 (known
as LAMOST I). The second active survey program (LAMOST II) began in
2017 September.
Liu+ (2019, J/ApJS/241/32) identified 16032 early-type stars through
measuring the equivalent widths of several absorption line profiles
using low-resolution spectra from the LAMOST low-resolution survey
(LRS) database. Guo+ (2022RAA....22b5009G 2022RAA....22b5009G) used the spectra from the
LAMOST MRS database to investigate the multiplicity properties of
early-type stars (Paper I).
In this study, we adopt all of the identified O- and B-type stars from
Liu+ (2019, J/ApJS/241/32) and Paper I to derive the stellar labels of
their spectra by applying the Stellar LAbel Machine (SLAM;
Zhang+ 2020ApJS..246....9Z 2020ApJS..246....9Z and 2020RAA....20...51Z 2020RAA....20...51Z).
File Summary:
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FileName Lrecl Records Explanations
--------------------------------------------------------------------------------
ReadMe 80 . This file
table1.dat 55 22292 The predicted stellar labels of 16032 LAMOST-LRS
(Liu+ 2019, J/ApJS/241/32) early-type stars
table2.dat 67 9287 The predicted stellar parameters of 9238 LAMOST-MRS
(Guo+ 2022RAA....22b5009G 2022RAA....22b5009G) early-type stars
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See also:
V/153 : LAMOST DR4 catalogs (Luo+, 2018)
V/164 : LAMOST DR5 catalogs (Luo+, 2019)
J/A+AS/139/231 : Early-type stars towards the Galactic Centre (Dufton+, 1999)
J/A+A/471/625 : VLT-FLAMES survey of massive stars (Trundle+, 2007)
J/A+A/496/841 : VLT-FLAMES survey of massive stars (Hunter+, 2009)
J/A+A/518/A1 : Galactic massive stars with AstraLux (Maiz Apellaniz, 2010)
J/A+A/539/A143 : Nearby B-stars stellar parameters & abundances (Nieva+, 2012)
J/ApJ/808/16 : Cannon: a new approach to determine abundances (Ness+, 2015)
J/other/RAA/16.138 : LAMOST cat. of early-type emission-line stars (Hou+, 2016)
J/ApJS/241/32 : OB stars from the LAMOST DR5 spectra (Liu+, 2019)
J/ApJS/253/22 : Ks absolute magnitudes from LAMOST for OB stars (Xiang+, 2021)
http://dr7.lamost.org/ : LAMOST DR7 home page
Byte-by-byte Description of file: table1.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- ObsID [215136/585213175] Star identifier
from LAMOST DR5
11- 18 F8.4 deg RAdeg Right Ascension in decimal degrees (J2000)
20- 26 F7.4 deg DEdeg [-9.2/61] Declination in decimal degrees (J2000)
28- 32 I5 --- SNR [-9999/999] Signal-to-Noise
34- 39 I6 K Teff [-36654/69857] Effective temperature
41- 43 F3.1 [cm/s2] log(g) [1/6.7] log surface gravity
45- 49 F5.2 [Sun] [M/H] [-2.6/1.1] Metallicity
51- 53 I3 km/s vsin(i) [0/497] Projected rotational velocity
55 A1 --- Flag Star flag (1)
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Note (1): Flag as follows:
I = A star with its parameters set by the training set.
O = A star whose's parameters are extrapolated from the SLAM
(Zhang+ 2020ApJS..246....9Z 2020ApJS..246....9Z and 2020RAA....20...51Z 2020RAA....20...51Z).
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Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
--------------------------------------------------------------------------------
1- 9 I9 --- ObsID [589004107/747815206] Star identifier
from LAMOST DR7
11- 18 F8.4 deg RAdeg Right Ascension (J2000)
20- 26 F7.4 deg DEdeg [-9.9/77.1] Declination (J2000)
28- 37 F10.4 d MJD [58024.8/58649.2] Modified Julian Date of
the observation
39- 41 I3 --- SNR-R [2/767] Signal-to-Noise in Red arm
43- 45 I3 --- SNR-B [2/728] Signal-to-Noise in Blue arm
47- 51 I5 K Teff [7081/58781] Effective temperature
53- 55 F3.1 [cm/s2] log(g) [1.5/5.4] log surface gravity
57- 61 F5.2 [Sun] [M/H] [-1.36/0.65] Metallicity
63- 65 I3 km/s vsin(i) [0/312] Projected rotational velocity
67 A1 --- Flag Star flag (1)
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Note (1): Flag as follows:
I = A star with its parameters set by the training set.
O = An early type star from the LAMOST-MRS database.
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History:
From electronic version of the journal
(End) Prepared by [AAS], Emmanuelle Perret [CDS] 08-Mar-2022