A 15.7-Minute AM CVn Binary Discovered in K2

M. J. Green; J. J. Hermes; T. R. Marsh; D. T. H. Steeghs; Keaton J. Bell; S. P. Littlefair; S. G. Parsons; E. Dennihy; J. T. Fuchs; J. S. Reding; B. C. Kaiser; R. P. Ashley; E. Breedt; V. S. Dhillon; N. P. Gentile Fusillo; P. Kerry; D. I. Sahman

doi:10.1093/mnras/sty1032

paper

A 15.7-Minute AM CVn Binary Discovered in K2

arXiv:1804.07138 · doi:10.1093/mnras/sty1032

Abstract

We present the discovery of SDSS J135154.46-064309.0, a short-period variable observed using 30-minute cadence photometry in K2 Campaign 6. Follow-up spectroscopy and high-speed photometry support a classification as a new member of the rare class of ultracompact accreting binaries known as AM CVn stars. The spectroscopic orbital period of $15.65 \pm 0.12$ \,minutes makes this system the fourth-shortest period AM CVn known, and the second system of this type to be discovered by the Kepler spacecraft. The K2 data show photometric periods at $15.7306 \pm 0.0003$ \,minutes, $16.1121 \pm 0.0004$ \,minutes and $664.82 \pm 0.06$ \,minutes, which we identify as the orbital period, superhump period, and disc precession period, respectively. From the superhump and orbital periods we estimate the binary mass ratio $q = M_{2} / M_{1} = 0.111 \pm 0.005$ , though this method of mass ratio determination may not be well calibrated for helium-dominated binaries. This system is likely to be a bright foreground source of gravitational waves in the frequency range detectable by LISA, and may be of use as a calibration source if future studies are able to constrain the masses of its stellar components.

arXiv comment13 pages, 11 figures

A 15.7-Minute AM CVn Binary Discovered in K2

Abstract

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