J/A+A/667/A44 LAMOST DR8 early-type stars statistical properties (Guo+, 2022)
The statistical properties of early-type stars from LAMOST DR8.
Guo Y., Liu C., Wang L., Wang J., Zhang B., Ji K., Han Z., Chen X.
<Astron. Astrophys. 667, A44 (2022)>
=2022A&A...667A..44G 2022A&A...667A..44G (SIMBAD/NED BibCode)
ADC_Keywords: Stars, early-type ; Radial velocities ; Optical
Keywords: methods: data analysis - methods: statistical - surveys -
stars: early-type
Abstract:
Massive binary stars play a crucial role in many astrophysical fields.
Investigating the statistical properties of massive binary stars is
essential to trace the formation of massive stars and constrain the
evolution of stellar populations. However, no consensus has been
achieved on the statistical properties of massive binary stars, mainly
due to the lack of a large and homogeneous sample of spectroscopic
observations.
To study the intrinsic binary fraction finb and distributions of
mass ratio f(q) and orbital period f(P) of early-type stars (comprise
of O/B/A-type stars) and investigate their dependencies on effective
temperature Teff, stellar metallicity [M/H] and the projection
velocity vsini, based on the homogeneous spectroscopic sample of from
the Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST)
Data Release Eight (DR8).
We collect 886 early-type stars, each with more than six observations
from the LAMOST DR8, and divide the sample into subgroups based on
their derived effective temperature (Teff), metallicity ([M/H]), and
projected rotational velocity (vsini). Radial velocity measurements
were archived from a prior study. A set of Monte-Carlo simulations,
following distributions of f(P) ∝ Pπand f(q) ∝
qγ were applied to the observed binary fraction to correct for
any observational biases. The uncertainties of the derived results
induced by the sample size and observation frequency are examined
systematically.
We found that finb increases with increasing Teff. For stars in
groups of B8-A, B4-B7, O-B3, the binary fractions are
finb=48%±10%, 60%±10%, and 76%±10%, respectively. The binary
fraction is positively correlated with metallicity for spectra in the
sample, with derived values of finb=44%±10%, 60%±10% and
72%±10% for spectra with metallicity spanning from [M/H]←0.55,
-0.55≤[M/H]←0.1, to [M/H]≥-0.1. Over all the vsini values we have
considered, the finb have constant values as ∼50%. It seems that
the binary population is relatively evenly distributed over a wide
range of vsini values, while the whole sample shows that most of the
stars are concentrated in low values of vsini (probably from strong
wind and magnetic braking of single massive stars), and in high values
of vsini (likely from the merge of binary stars) in cases. Stellar
evolution and binary interaction may be partly responsible for this.
In case of observations with more than six observations, we have
derived π=-0.9±0.35, -0.9±0.35, and -0.9±0.35, and
γ=-1.9±0.9, -1.1±0.9 and -2±0.9 for O-B3, B4-B7, B8-A type
stars, respectively. There are no correlations being found between
π(γ) and Teff, and neither for π(γ) and [M/H]. The
uncertainties of the distribution decrease towards a larger sample
size with higher observational cadence.
Description:
File table2 contains the observation ID, coordinates, MJD date, S/N,
Teff, [M/H], vsini, RV, and the uncertainty for 886 early-type stars
from LAMOST DR8.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table2.dat 81 6835 List of basic information for 886 early-type
stars from LAMOST DR8
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See also:
J/ApJS/257/54 : Early-type star param. from LAMOST LRS + MRS (Guo+, 2021)
Byte-by-byte Description of file: table2.dat
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Bytes Format Units Label Explanations
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1- 9 I9 --- OBSID The observation ID
11- 19 F9.5 deg RAdeg Right Ascension (J2000)
21- 28 F8.5 deg DEdeg Right Ascension (J2000)
30- 39 F10.4 d Date MJD date
41- 43 I3 --- SNR Signal to noise ratio
45- 49 I5 K Teff Effective temperature (1)
51- 59 F9.6 [-] [M/H] Metallicity (1)
61- 63 I3 km/s vsini Projected rotational velocity (1)
65- 75 F11.6 km/s RV Radial velocity
77- 81 F5.2 km/s e_RV The uncertainty of radial velocity
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Note (1): the data from Guo et al. (2021ApJS..257...54G 2021ApJS..257...54G, Cat. J/ApJS/257/54)
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Acknowledgements:
Yanjun Guo, guo(at)mpia-hd.mpg.de
(End) Patricia Vannier [CDS] 22-Sep-2022