The quest for companions to post-common envelope binaries. II. NSVS14256825 and HS0705+6700

TL;DR

This study reports new eclipse timing variations in two post-common envelope binaries, suggesting the presence of substellar companions, including a giant planet and a brown dwarf, thus contributing to understanding planetary systems around evolved binaries.

Contribution

It provides new observational evidence for substellar companions in post-common envelope binaries, refining parameters and strengthening the case for their existence.

Findings

NSVS14256825 likely hosts a giant planet (~12 M_Jup).

HS0705+6700's eclipse variations are consistent with a brown dwarf (~31 M_Jup).

Period variations are explained by third-body orbiting companions.

Abstract

We report new mid-eclipse times of the two close binaries NSVS14256825 and HS0705+6700, harboring an sdB primary and a low-mass main-sequence secondary. Both objects display clear variations in the measured orbital period, which can be explained by the action of a third object orbiting the binary. If this interpretation is correct, the third object in NSVS14256825 is a giant planet with a mass of roughly 12 M_Jup. For HS0705+6700, we provide evidence that strengthens the case for the suggested periodic nature of the eclipse time variation and reduces the uncertainties in the parameters of the brown dwarf implied by that model. The derived period is 8.4 yr and the mass is 31 M_Jup, if the orbit is coplanar with the binary. This research is part of the PlanetFinders project, an ongoing collaboration between professional astronomers and student groups at high schools.