Beer analysis of kepler and CoRoT light curves. IV. Discovery of four new low-mass white dwarf companions in the Kepler data

S. Faigler, I. Kull, T. Mazeh, F. Kiefer, D. W. Latham, S. Bloemen

Research output: Contribution to journalArticlepeer-review

Abstract

We report the discovery of four short-period eclipsing systems in the Kepler light curves, consisting of an A-star primary and a low-mass white dwarf (WD) secondary (dA+WD) - KIC 4169521, KOI-3818, KIC 2851474, and KIC 9285587. The systems show BEaming, Ellipsoidal and Reflection (BEER) phase modulations together with primary and secondary eclipses. These add to the 6 Kepler and 18 WASP short-period eclipsing dA+WD binaries that were previously known. The light curves, together with follow-up spectroscopic observations, allow us to derive the masses, radii, and effective temperatures of the two components of the four systems. The orbital periods, of 1.17-3.82 days, and WD masses, of 0.19-0.22 Mo, are similar to those of the previously known systems. The WD radii of KOI-3818, KIC 2851474, and KIC 9285587 are 0.026, 0.035, and 0.026 Ro, respectively, the smallest WD radii derived so far for short-period eclipsing dA+WD binaries. These three binaries extend the previously known population to older systems with cooler and smaller WD secondaries. KOI-3818 displays evidence for a fast-rotating primary and a minute but significant eccentricity, ∼1.5 × 10-3. These features are probably the outcome of the mass-transfer process.

Original languageEnglish
Article number26
JournalAstrophysical Journal
Volume815
Issue number1
DOIs
StatePublished - 10 Dec 2015

Funding

FundersFunder number
Seventh Framework Programme291352

    Keywords

    • stars: individual (KIC 4169521, KIC 6515722, KOI-3818, KIC 2851474 KIC 9285587)
    • white dwarfs

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