PTF1 J085713+331843, a new post-common-envelope binary in the orbital period gap of cataclysmic variables

July 2017 • 2017MNRAS.468.3109V

Authors • van Roestel, J. • Groot, P. J. • Levitan, D. • Prince, T. A. • Bloemen, S. • Marsh, T. R. • Dhillon, V. S. • Shupe, D. • Laher, R.

Abstract • We report the discovery and analysis of PTF1 J085713+331843, a new eclipsing post-common-envelope detached white-dwarf-red-dwarf binary with a 2.5 h orbital period discovered by the Palomar Transient Factory. ULTRACAM multicolour photometry over multiple orbital periods reveals a light curve with a deep flat-bottomed primary eclipse and a strong reflection effect. Phase-resolved spectroscopy shows broad Balmer absorption lines from the DA white dwarf and phase-dependent Balmer emission lines originating on the irradiated side of the red dwarf. The temperature of the DA white dwarf is T_WD = 25 700 ± 400 K and the spectral type of the red dwarf is M3-M5. A combined modelling of the light curve and the radial velocity variations results in a white dwarf mass of M_WD = 0.61^{+0.18}_{-0.17} M_{⊙} and radius of R_WD = 0.0175^{+0.0012}_{-0.0011} R_{⊙}, and a red dwarf mass and radius of M_RD = 0.19^{+0.10}_{-0.08} M_{⊙} and R_RD = 0.24^{+0.04}_{-0.04} R_{⊙}. The system is either a detached cataclysmic variable or has emerged like from the common-envelope phase at nearly its current orbital period. In {∼ }70 Myr, this system will become a cataclysmic variable in the period gap.

Links

• SIMBAD http://simbad.u-strasbg.fr/simbo.pl?bibcode=2017MNRAS.468.3109V
• PDF http://academic.oup.com/mnras/pdf-lookup/468/3/3109
• PREPRINT http://arxiv.org/abs/1704.01182
• ELECTR https://doi.org/10.1093%2Fmnras%2Fstx625