Extremely low-mass white dwarf stars observed in Gaia DR2 and LAMOST DR8

Abstract

We present the first results from our ongoing project to study extremely low mass (ELM) white dwarfs (WDs) ($M$ $\le$ 0.3$M_{\sun}$) with the Large Sky Area Multi-Object Fibre Spectroscopic Telescope (LAMOST) spectra. Based on the LAMOST DR8 spectral database, we analyzed 136 ELM WD candidates selected from $Gaia$ DR2 data and 12 known objects previously identified by the ELM Survey. The atmospheric parameters and radial velocities of these stars were obtained by fitting the LAMOST low-resolution spectra. After comparing the atmospheric parameters of the 12 known objects from this work to the results reported by the ELM Survey, we demonstrated the potential of LAMOST spectra in probing into the nature of ELM WDs. Based on the atmospheric parameters and $Gaia$ EDR3 data, we identified 21 new high-probability ELM WDs with masses $M$ $\le$ 0.3$M_{\sun}$ and parallax estimates that agree to within a factor of 3. Two of them, J0338+4134 and J1129+4715, show significant radial velocity variability and are very likely to be binary systems containing at least one ELM WD.

6 figures, 5 tables, accepted for publication in ApJ

References in corpus (22)

• The Optical to Mid-Infrared Extinction Law Based on the APOGEE, Gaia DR2, Pan-STARRS1, SDSS, APASS, 2MASS and WISE Surveys
• The ELM Survey. I. A Complete Sample of Extremely Low Mass White Dwarfs
• A selection of hot subluminous stars in the GALEX survey II. Subdwarf atmospheric parameters
• Science with the TianQin Observatory: Preliminary results on Galactic double white dwarf binaries
• The ELM Survey. VIII. 98 Double White Dwarf Binaries
• Observationally driven Galactic double white dwarf population for LISA
• The timescale of low-mass proto-helium white dwarf evolution
• The Thermal Evolution of the Donors in AM CVn Binaries
• Near-Infrared Photometry of Globular Clusters Towards the Galactic Bulge: Observations and Photometric Metallicity Indicators
• Post-merger evolution of carbon-oxygen + helium white dwarf binaries and the origin of R Coronae Borealis and extreme helium stars
• Gaia Data Release 2 Catalogue of Extremely-low Mass White Dwarf Candidates
• Gaia EDR3 Parallax Zero-point Offset based on W Ursae Majoris-type Eclipsing Binaries
• Birth of the ELMs: a ZTF survey for evolved cataclysmic variables turning into extremely low-mass white dwarfs
• Pruning The ELM Survey: Characterizing Candidate Low-Mass White Dwarfs Through Photometric Variability
• PSR J1012+5307: a millisecond pulsar with an extremely low-mass white dwarf companion
• Hot subdwarf Atmospheric parameters, Kinematics, and Origins -- Based on 1587 hot subdwarf stars observed in Gaia DR2 and LAMOST DR7
• The white dwarf mass-radius relation and its dependence on the hydrogen envelope
• Radial velocity variability and evolution of hot subdwarf stars
• The ELM Survey South. I. An Effective Search for Extremely Low Mass White Dwarfs
• Mass Transfer and Stellar Evolution of the White Dwarfs in AM CVn Binaries
• LAMOST J0140355+392651: An evolved cataclysmic variable donor transitioning to become an extremely low mass white dwarf
• Convection and rotation boosted prescription of magnetic braking: application to the formation of extremely low-mass white dwarfs

Cited by in corpus (11)

• The ELM Survey South. II. Two dozen new low mass white dwarf binaries
• A Systematic Search for Short-period Close White Dwarf Binary Candidates Based on Gaia EDR3 Catalog and Zwicky Transient Facility Data
• A seven-Earth-radius helium-burning star inside a 20.5-min detached binary
• FX UMa: A New Heartbeat Binary System with Linear and Non-linear Tidal Oscillations and delta Sct Pulsations
• Compact Objects in close orbits as Gravitational Wave Sources: Formation Scenarios and Properties
• Discovery of four new EL CVn-type binaries in the Gaia eclipsing binaries
• J0526+5934: a peculiar ultra-short period double white dwarf
• Unveiling the evolutionary state of three B supergiant stars: PU Gem, $\epsilon$ CMa and $\eta$ CMa
• Searching for new variable white dwarfs: The discovery of the three new pulsating and three new binary systems
• Formation of Extremely Low-mass White Dwarf Binaries Undergoing Enhanced Angular Momentum Loss
• Rotating strange dwarfs and their indistinguishability from white dwarfs