Stellar Parameters and Orbital Period Estimates for Composite-Spectrum sdB+MS Binaries from LAMOST

Abstract

Hot subdwarf (sdB) stars in binary systems with main-sequence (MS) companions provide valuable insights into mass transfer and envelope ejection processes in binary evolution. Their mass ratios, orbital periods, and stellar properties encode key information about their evolutionary histories. In this work, we analyze a sample of 123 composite-spectrum sdB+MS binaries identified from the Large Sky Area Multi-Object Fiber Spectroscopic Telescope Low-Resolution Survey (LAMOST-LRS) Data Release (DR) 8. We adopt atmospheric parameters from spectral decomposition and estimate stellar masses and radii using theoretical evolutionary tracks. Radial velocities for both the hot subdwarfs and cool companions are measured independently through cross-correlation with synthetic templates. Orbital periods are statistically estimated using single-epoch RV separations and a Monte Carlo method that accounts for random inclination and orbital phase. We find that sdB masses are narrowly distributed around 0.5 Msun, consistent with expectations for core helium-burning stars, while MS companion masses span 0.6-1.9 Msun, with most falling between 1.0 and 1.4 Msun. The inferred orbital-period distribution shows a clear concentration toward long periods, broadly consistent with expectations for binaries formed through stable Roche-lobe overflow. Given that our sample consists of composite-spectrum sdB binaries, mainly sdB+FGK systems, the prevalence of long periods is largely driven by observational selection effects rather than the intrinsic period distribution of the sdB binary population. This study provides one of the largest uniform catalogs of composite spectrum sdB binaries to date, offering new observational constraints on their physical properties and formation channels.

References in corpus (32)

• The Astropy Project: Sustaining and Growing a Community-oriented Open-source Project and the Latest Major Release (v5.0) of the Core Package
• PARSEC: stellar tracks and isochrones with the PAdova and TRieste Stellar Evolution Code
• Gaia Data Release 3: Summary of the content and survey properties
• Estimating distances from parallaxes. V: Geometric and photogeometric distances to 1.47 billion stars in Gaia Early Data Release 3
• The Origin of Subdwarf B Star (I): the Formation Channels
• A Grid of NLTE Line-Blanketed Model Atmospheres of O-type Stars
• The origin of sdB stars (II)
• Improving PARSEC models for very low mass stars
• PARSEC evolutionary tracks of massive stars up to $350M_{\odot }$ at metallicities 0.0001$\le Z\le$0.04
• Hot subluminous stars
• The Potential of Asteroseismology for Hot, Subdwarf B Stars: A New Class of Pulsating Stars?
• A binary model for the UV-upturn of elliptical galaxies (MNRAS version)
• A selection of hot subluminous stars in the GALEX survey II. Subdwarf atmospheric parameters
• Hot subdwarfs from the ESO Supernova Ia Progenitor Survey - I. Atmospheric parameters and cool companions of sdB stars
• Hot subdwarf binaries from the MUCHFUSS project - Analysis of 12 new systems and a study of the short-period binary population
• Deriving the stellar labels of LAMOST spectra with Stellar LAbel Machine (SLAM)
• Binary Population Synthesis
• Self-consistent Stellar Radial Velocities from LAMOST Medium-Resolution Survey (MRS) DR7
• The orbital periods of subdwarf B binaries produced by the first stable Roche overflow channel
• The orbits of subdwarf-B + main-sequence binaries. II. Three eccentric systems; BD+29 3070, BD +34 1543 and Feige 87
• The orbits of subdwarf-B + main-sequence binaries: III. The period - eccentricity distribution
• Testing eccentricity pumping mechanisms to model eccentric long period sdB binaries with MESA
• The orbits of subdwarf B + main-sequence binaries. I: The sdB+G0 system PG 1104+243
• The orbital period -- mass ratio relation of wide sdB+MS binaries and its application to the stability of RLOF
• Composite hot-subdwarf binaries -- I. The spectroscopically confirmed sdB sample
• PG1018-047: the longest period subdwarf B binary
• Hot subdwarf stars identified in LAMOST DR8 with single-lined and composite spectra
• The masses of hot subdwarfs
• The first heavy-metal hot subdwarf composite binary SB 744
• Orbital and atmospheric parameters of two wide O-type subdwarf binaries: BD$-$11${}^{\mathrm{o}}$162 and Feige 80
• Radial velocity monitoring of long period hot subdwarf + main sequence binaries with HERMES@Mercator
• Population synthesis of hot subdwarf B stars with COMPAS: on the observed Galactic population