Constraints on the origin of the massive, hot, and rapidly rotating magnetic white dwarf RE J 0317-853 from an HST parallax measurement

Abstract

Aims: We use the parallax measurements of RE J 0317-853 to determine its mass, radius, and cooling age and thereby constrain its evolutionary origins.
Methods: We observed RE J 0317-853 with the Hubble Space Telescope's Fine Guidance Sensor to measure the parallax of RE J 0317-853 and its binary companion, the non-magnetic white dwarf LB 9802. In addition, we acquired spectra of comparison stars with the Boller & Chivens spectrograph of the SMARTS telescope to correct the parallax zero point. For the corrected parallax, we determine the radius, mass, and the cooling age with the help of evolutionary models from the literature.
Results: The properties of RE J 0317-853 are constrained using the parallax information. We discuss the different cases of the core composition and the uncertain effective temperature. We confirm that RE J 0317-853 is close to the Chandrasekhar's mass limit in all cases and almost as old as its companion LB 9802.
Conclusions: The precise evolutionary history of RE J 0317-853 depends on our knowledge of its effective temperature. It is possible that it had a single star progenitor possible if we assume that the effective temperature is at the cooler end of the possible range from 30 000 to 50 000 K; if T_eff is instead at the hotter end, a binary-merger scenario for RE J 0317-853 becomes more plausible.

Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS5-26555. The Guide Star Catalogue-II is a joint project of the Space Telescope Science Institute and the Osservatorio Astronomico di Torino.