Hot subdwarf stars identified in LAMOST DR8 with single-lined and composite spectra

Abstract

222 hot subdwarf stars were identified with LAMOST DR8 spectra, among which 131 stars show composite spectra and have been decomposed, while 91 stars present single-lined spectra. Atmospheric parameters of all sample stars were obtained by fitting Hydrogen (H) and Helium (He) line profiles with synthetic spectra. Two long-period composite sdB binaries were newly discovered by combining our sample with the non-single star data from Gaia DR3. One of the new systems presents the highest eccentricity (i.e., 0.5 +/- 0.09) among known wide sdB binaries, which is beyond model predictions. 15 composite sdB stars fall in the high probability binary region of RUWE-AEN plane, and deserve priority follow-up observations to further study their binary nature. A distinct gap is clearly presented among temperatures of cool companions for our composite-spectra sample. But we could not come to a conclusion whether this feature is connected to the formation history of hot subdwarf stars before their binary natures are confirmed.

21 pages, 11 figures, 3 tables, Accepted for publication in ApJ

References in corpus (20)

• The Gaia mission
• A Grid of NLTE Line-Blanketed Model Atmospheres of Early B-type Stars
• A selection of hot subluminous stars in the GALEX survey II. Subdwarf atmospheric parameters
• White dwarf and subdwarf stars in the Sloan Digital Sky Survey Data Release 14
• The population of hot subdwarf stars studied with Gaia -- IV. Catalogues of hot subluminous stars based on Gaia EDR3
• 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
• Composite hot-subdwarf binaries -- I. The spectroscopically confirmed sdB sample
• Hot subdwarf Atmospheric parameters, Kinematics, and Origins -- Based on 1587 hot subdwarf stars observed in Gaia DR2 and LAMOST DR7
• Evolution models of helium white dwarf--main sequence star merger remnants
• Hot subdwarf stars identified in Gaia DR2 with spectra of LAMOST DR6 and DR7 I. Single-lined spectra
• Radial velocity variability and evolution of hot subdwarf stars
• Astrometric excess noise in Gaia EDR3 and the search for X-ray binaries
• A possible formation channel for blue hook stars in globular cluster
• Shell helium-burning hot subdwarf B stars as candidates for blue large-amplitude pulsators
• Searching for Hot Subdwarf Stars in LAMOST DR1-II. Pure spectroscopic identification method for hot subdwarfs
• The first heavy-metal hot subdwarf composite binary SB 744
• A possible formation channel for blue hook stars in globular cluster - II. Effects of metallicity, mass ratio, tidal enhancement efficiency and helium abundance
• Evolutionary Constraints on the Long-period Subdwarf B Binary PG 1018-047

Cited by in corpus (7)

• Formation of long-period post-common-envelope binaries I. No extra energy is needed to explain oxygen-neon white dwarfs paired with AFGK-type main-sequence stars
• Mass distribution for single-lined hot subdwarf stars in LAMOST
• The first massive compact companion in a wide orbit around a hot subdwarf star
• Advanced Classification of Hot Subdwarf Binaries Using Artificial Intelligence Techniques and Gaia DR3 data
• A 500 pc volume-limited sample of hot subluminous stars II. Atmospheric parameters, mass distribution, and kinematics
• Short-Period Variables in TESS Full-Frame Image Light Curves Identified via Convolutional Neural Networks
• Stellar Parameters and Orbital Period Estimates for Composite-Spectrum sdB+MS Binaries from LAMOST