Is there a circumbinary planet around NSVS 14256825

摘要: The cyclic behaviour of (O-C) residuals eclipse timings in the sdB+M eclipsing binary NSVS 14256825 was previously attributed to one or two Jovian-type circumbinary planets. We report 83 new that not only fill gaps those already published but also extend time span diagram by three years. Based on archival and our data spanning over more than 17 years we re-examined up date system (O-C). revealed systematic, quasi-sinusoidal variation deviating from an older linear ephemeris about 100 s. It exhibits a maximum near JD 2,456,400 unknown. consider most credible explanations variability: light propagation due presence invisible companion distant orbit, magnetic cycles reshaping components, known as Applegate Lanza-Rodono effect. found latter mechanism is unlikely insufficient energy budget M-dwarf secondary. In framework third-body hypothesis, obtained meaningful constraints Keplerian parameters putative its mass. Our best-fitting model indicates observed quasi-periodic variability can be explained brown dwarf with minimal mass 15 Jupiter masses rather planet, orbiting moderately elliptical orbit (~ 0.175) period ~ 10 analysis rules out planets proposed earlier.