A Third Hot White Dwarf Companion Detected by Kepler

摘要: We have found a system listed in the Kepler Binary Catalog (3.273 day period; Prsa et al. 2010) that we determined is comprised of low-mass, thermally-bloated, hot white dwarf orbiting an A star about 2.3 solar masses. In this work designate object, KIC 10657664, simply as KHWD3. use transit depth ~0.66%, eclipse ~1.9%, and regular smooth periodic variations at orbital frequency twice to analyze parameters. The are identified with classical ellipsoidal light variation illumination effects, newly utilized Doppler boosting effect. Given measured values R/a inclination angle binary, both ELV DB effects mostly sensitive mass ratio, q = M_2/M_1, binary. two yield which somewhat inconsistent - presumably due unidentified systematic but nonetheless provide quite useful set possibilities for (either 0.18 +/- 0.03 M_Sun or 0.37 0.08 M_Sun). All other parameters fairly robustly. particular, show has radius 0.15 0.01 R_Sun extremely bloated over it would fully degenerate effective temperature T_eff 14,100 350 K. evolution scenarios models discussed. suggest progenitor binary was primary ~2.2 (the current dwarf) secondary ~1.4 system). compare new three dwarfs binaries likely were formed via stable Roche-lobe overflow (KOI-74, KOI-81, Regulus).