A White Dwarf-Main Sequence Binary Unveiled by Time-Domain Observations from LAMOST and TESS

Abstract

We report a single-lined white dwarf-main sequence binary system, LAMOST J172900.17+652952.8, which is discovered by LAMOST's medium resolution time-domain surveys. The radial velocity semi-amplitude and orbital period of the optical visible star are measured by using the Palomar 200-inch telescope follow-up observations and the light curves from TESS. Thus the mass function of the invisible candidate white dwarf is derived, $f(M_2)=0.120\pm 0.003M_{\odot }$. The mass of the visible star is measured based on the spectral energy distribution fitting, $M_1$ = $0.81_{-0.06}^{+0.07}{M}_{\odot }$. Hence, the mass of its invisible companion is $M_2\gtrsim 0.63M_{\odot }$. The companion ought to be a compact object rather than a main-sequence star owing to the mass ratio $q=M_2/M_1\gtrsim 0.78$ and the single-lined spectra. The compact object is likely to be a white dwarf except for small inclination angle, $i\lesssim 40^{\circ }$. By using the GALEX NUV flux, the effective temperature of the white dwarf candidate is constrained as $T_{\mathrm{eff}}^{\mathrm{WD}}\lesssim 12000-13500$ K. It is difficult to detect white dwarfs which are outshone by their bright companions via single-epoch optical spectroscopic surveys. Therefore, the optical time-domain surveys can play an important role in unveiling invisible white dwarfs and other compact objects in binaries.

15 pages, 6 figures, ApJ, 936, 33

References in corpus (22)

• The Transiting Exoplanet Survey Satellite
• On the Spectral Evolution of Hot White Dwarf Stars. I. A Detailed Model-Atmosphere Analysis of Hot White Dwarfs from SDSS DR12
• Found: The missing blue opacity in atmosphere models of cool hydrogen white dwarfs
• A wide star-black-hole binary system from radial-velocity measurements
• The 100 pc White Dwarf Sample in the SDSS Footprint
• The Joker: A custom Monte Carlo sampler for binary-star and exoplanet radial velocity data
• White dwarf and subdwarf stars in the Sloan Digital Sky Survey Data Release 14
• ARIADNE: Measuring accurate and precise stellar parameters through SED fitting
• The Gaia-ESO Survey: double, triple and quadruple-line spectroscopic binary candidates
• White dwarf-main sequence binaries from Gaia EDR3: the unresolved 100pc volume-limited sample
• Double-, triple-line spectroscopic candidates in the LAMOST Medium-Resolution Spectroscopic Survey
• LAMOST Medium-Resolution Spectroscopic Survey (LAMOST-MRS): Scientific goals and survey plan
• GALExtin: An alternative online tool to determine the interstellar extinction in the Milky Way
• The population of white dwarf-main sequence binaries in the SDSS DR 12
• The white dwarf binary pathways survey - II. Radial velocities of 1453 FGK stars with white dwarf companions from LAMOST DR4
• The White Dwarf Binary Pathways Survey IV: Three close white dwarf binaries with G-type secondary stars
• A Method to Search for Black Hole Candidates with Giant Companions by LAMOST
• Multi-band photometry and spectroscopy of an all-sky sample of bright white dwarfs
• Mining for Candidates of Galactic Stellar-mass Black Hole Binaries with LAMOST
• White-dwarf+main-sequence binaries identified from the tenth data release of Solan Digital Sky Survey
• Compact Object Candidates with K/M-dwarf Companions from LAMOST Low-resolution Survey
• A long-period pre-ELM system discovered from LAMOST medium-resolution survey

Cited by in corpus (1)

• Searching for compact objects in binaries with Gaia DR3