Testing the white dwarf mass-radius relation and comparing optical and far-UV spectroscopic results with Gaia DR2, HST and FUSE

Abstract

Observational tests of the white dwarf mass-radius relationship have always been limited by the uncertainty in the available distance measurements. Most studies have focused on Balmer line spectroscopy because these spectra can be obtained from ground based observatories, while the Lyman lines are only accessible to space based UV telescopes. We present results using parallax data from Gaia DR2 combined with space based spectroscopy from HST and FUSE covering the Balmer and Lyman lines. We find that our sample supports the theoretical relation, although there is at least one star which is shown to be inconsistent. Comparison of results between Balmer and Lyman line spectra shows they are in agreement when the latest broadening tables are used. We also assess the factors which contribute to the error in the mass-radius calculations and confirm the findings of other studies which show that the spread in results for targets where multiple spectra are available is larger than the statistical error. The uncertainty in the spectroscopically derived log g parameter is now the main source of error rather than the parallax. Finally, we present new results for the radius and spectroscopic mass of Sirius B which agree with the dynamical mass and mass-radius relation within 1 sigma.

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Cited by in corpus (9)

• Fundamental parameter accuracy of DA and DB white dwarfs in Gaia Data Release 2
• The gravitational redshift of Sirius B
• Sub-percent Photometry: Faint DA White Dwarf Spectophotometric Standards for Astrophysical Observatories
• A Gravitational Redshift Measurement of the White Dwarf Mass-Radius Relation
• Single magnetic white dwarfs with Balmer emission lines: A small class with consistent physical characteristics as possible signposts for close-in planetary companions
• Dynamical Masses and Ages of Sirius-like Systems
• Synthesis of radioactive elements in novae and supernovae and their use as a diagnostic tool
• A Correction for GALEX Spectroscopic UV Flux Distributions from Comparisons with CALSPEC and IUE
• Improving white dwarfs as chronometers with Gaia parallaxes and spectroscopic metallicities