Is there a circumbinary planet around NSVS 14256825?

Abstract

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

17 pages, 9 figures, 4 tables, accepted to AJ

References in corpus (13)

• Achieving better than 1 minute accuracy in the Heliocentric and Barycentric Julian Dates
• The sdB+M Eclipsing System HW Virginis and its Circumbinary Planets
• First versus second generation planet formation in post common envelope binary (PCEB) planetary systems
• The HU Aqr planetary system hypothesis revisited
• On the HU Aquarii planetary system hypothesis
• Extrasolar planet detection by binary stellar eclipse timing: evidence for a third body around CM Draconis
• The First Science Results from SPHERE: Disproving the Predicted Brown Dwarf around V471 Tau
• Hunting high and low: XMM monitoring of the eclipsing polar HU Aquarii
• Period and amplitude variations in post-common-envelope eclipsing binaries observed with SuperWASP
• The Pulsating sdB+M Eclipsing System NY Virginis and its Circumbinary Planets
• Tatooine's Future: The Eccentric Response of Kepler's Circumbinary Planets to Common-Envelope Evolution of their Host Stars
• Binary star influence on post-main-sequence multi-planet stability
• Testing the planetary models of HU Aquarii

Cited by in corpus (5)

• Solar System Physics for Exoplanet Research
• The binary mass ratios of circumbinary planet hosts
• New Observations of the Eclipsing Binary System NY Vir and its Candidate Circumbinary Planets
• Possible substellar companions in dwarf eclipsing binaries: SDSS J143547.87+373338.5, NSVS 7826147, and NSVS 14256825
• Investigation on the Orbital Period Variations of NN Ser: Implications for the Hypothetical Planets, the Applegate Mechanism and the Orbital Stability