TWO POSSIBLE CIRCUMBINARY PLANETS IN THE ECLIPSING POST-COMMON ENVELOPE SYSTEM NSVS 14256825

Abstract

We present an analysis of eclipse timings of the post-common envelope binary\nNSVS 14256825, which is composed of an sdOB star and a dM star in a close orbit\n(P_{orb} = 0.110374 days). High-speed photometry of this system was performed\nbetween July, 2010 and August, 2012. Ten new mid-eclipse times were analyzed\ntogether with all available eclipse times in the literature. We revisited the\n(O-C) diagram using a linear ephemeris and verified a clear orbital period\nvariation. On the assumption that these orbital period variations are caused by\nlight travel time effects, the (O-C) diagram can be explained by the presence\nof two circumbinary bodies, even though this explanation requires a longer\nbaseline of observations to be fully tested. The orbital periods of the best\nsolution would be P_c ~ 3.5 years and P_d ~ 6.9 years. The corresponding\nprojected semi-major axes would be a_c i_c ~ 1.9 AU and a_d i_d ~ 2.9 AU. The\nmasses of the external bodies would be M_c ~ 2.9 M_{Jupiter} and M_d ~ 8.1\nM_{Jupiter}, if we assume their orbits are coplanar with the close binary.\nTherefore NSVS 14256825 might be composed of a close binary with two\ncircumbinary planets, though the orbital period variations is still open to\nother interpretations.\n