A circumbinary planet in orbit around the short-period white dwarf eclipsing binary RR Cae
Abstract
By using six newly determined mid-eclipse times together with those collected from the literature, we have found that the observed minus calculated (O-C) curve of RR Cae shows a cyclic change with a period of 11.9 yr and an amplitude of 14.3 s while it undergoes an upward parabolic variation [revealing a long-term period increase at a rate of ?]. The cyclic change was analysed 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 M3sin i'= 4.2(± 0.4) MJup, suggesting that it is a circumbinary giant planet when its orbital inclination is larger than 17?6. 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; and it cannot 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 yr) cyclic variation, which may reveal the presence of another giant circumbinary planet in a wide orbit.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- May 2012
- DOI:
- 10.1111/j.1745-3933.2012.01228.x
- arXiv:
- arXiv:1201.4205
- Bibcode:
- 2012MNRAS.422L..24Q
- Keywords:
-
- binaries: close;
- binaries: eclipsing;
- stars: individual: RR Cae;
- planetary systems;
- white dwarfs;
- Astrophysics - Solar and Stellar Astrophysics;
- Astrophysics - Earth and Planetary Astrophysics
- E-Print:
- It will be published in the MNRAS