On the dynamical stability of the proposed planetary system orbiting NSVS 14256825

Abstract

We present a detailed dynamical analysis of the orbital stability of the two\ncircumbinary planets recently proposed to orbit the evolved eclipsing binary\nstar system NSVS 14256825. As is the case for other recently proposed\ncircumbinary planetary systems detected through the timing of mutual eclipses\nbetween the central binary stars, the proposed planets do not stand up to\ndynamical scrutiny. The proposed orbits for the two planets are extremely\nunstable on timescales of less than a thousand years, regardless of the mutual\ninclination between the planetary orbits.\n For the scenario where the planetary orbits are coplanar, a small region of\nmoderate stability was observed, featuring orbits that were somewhat protected\nfrom destabilisation by the influence of mutual 2:1 mean-motion resonance\nbetween the orbits of the planets. Even in this stable region, however, the\nsystems tested typically only survived on timescales of order 1 million years,\nfar shorter than the age of the system.\n Our results suggest that, if there are planets in the NSVS 14256825 system,\nthey must move on orbits dramatically different to those proposed in the\ndiscovery work. More observations are clearly critically required in order to\nconstrain the nature of the suggested orbital bodies.\n