A Circumbinary Planet in Orbit Around the Short-Period White-Dwarf Eclipsing Binary RR Cae
Abstract
By using six new determined mid-eclipse times together with those collected from the literature, we found that the Observed-Calculated (O-C) curve of RR Cae shows a cyclic change with a period of 11.9 years and an amplitude of 14.3s, while it undergoes an upward parabolic variation (revealing a long-term period increase at a rate of dP/dt =+4.18(+-0.20)x10^(-12). The cyclic change was analyzed for the light-travel time effect that arises from the gravitational influence of a third companion. The mass of the third body was determined to be M_3*sin i' = 4.2(+-0.4) M_{Jup} suggesting that it is a circumbinary giant planet when its orbital inclination is larger than 17.6 degree. The orbital separation of the circumbinary planet from the central eclipsing binary is about 5.3(+-0.6)AU. The period increase is opposite to the changes caused by angular momentum loss via magnetic braking or/and gravitational radiation, nor can it be explained by the mass transfer between both components because of its detached configuration. These indicate that the observed upward parabolic change is only a part of a long-period (longer than 26.3 years) cyclic variation, which may reveal the presence of another giant circumbinary planet in a wide orbit.
Cite
@article{arxiv.1201.4205,
title = {A Circumbinary Planet in Orbit Around the Short-Period White-Dwarf Eclipsing Binary RR Cae},
author = {S. -B. Qian and L. Liu and L. -Y. Zhu and Z. -B. Dai and E. Fernandez Lajus and G. L. Baume},
journal= {arXiv preprint arXiv:1201.4205},
year = {2015}
}
Comments
It will be published in the MNRAS