CIRCUMBINARY PLANETS ORBITING THE RAPIDLY PULSATING SUBDWARF B-TYPE BINARY NY Vir

Abstract

We report here the tentative discovery of a Jovian planet in orbit around the rapidly pulsating subdwarf B-type (sdB-type) eclipsing binary NY Vir. By using new determined eclipse times together with those collected from the literature, we detect that the observed-calculated (O-C) curve of NY Vir shows a smallamplitude cyclic variation with a period of 7.9 years and a semiamplitude of 6.1 s, while it undergoes a downward parabolic change (revealing a period decrease at a rate ofṖ = −9.2 × 10 −12 ). The periodic variation was analyzed for the lighttravel time effect via the presence of a third body. The mass of the tertiary companion was determined to be M 3 sin i ′ = 2.3(±0.3) M Jupiter when a total mass of 0.60 M ⊙ for NY Vir is adopted. This suggests that it is most probably a giant circumbinary planet orbiting NY Vir at a distance of about 3.3 astronomical units (AU). Since the rate of period decrease can not be explained by true angular momentum loss caused by gravitational radiation or/and magnetic braking, the observed downward parabolic change in the O-C diagram may be only a part of a long-period (longer than 15 years) cyclic variation, which may reveal the presence of another Jovian planet (∼ 2.5M Jupiter ) in the system.

Period and amplitude variations in post-common-envelope eclipsing binaries observed with SuperWASP

“…A steady period decrease was observed in the O−C diagram by Kilkenny (2011);Çamurdan et al (2012); Qian et al (2012), and is independently supported by our new SuperWASP timings. Qian et al argue that this is unlikely to be caused by the Applegate mechanism, gravitational radiation or magnetic braking, due to its magnitude and the fully convective nature of the stars, and suggest instead that it is part of a long-term (>15 y) cyclic variation associated with a circumbinary planet; furthermore, they claim that the O−C diagram provides evidence for a shorter-period fourth body in the system.…”

“…Kilkenny et al (1998) published the discovery paper for NY Vir, and provided eclipse timings and an ephemeris for it between 1996 and 2010 (Kilkenny et al 2000;Kilkenny 2011). Additional times are given in Çamurdan et al (2012) and Qian et al (2012); the latter also provides the revised ephemeris:…”

Long-Term Decrease and Cyclic Variation in the Orbital Period of the Eclipsing Dwarf Nova V2051 Oph

“…To search for planets and brown dwarfs around evolved binary stars, since 2006 we have monitored some evolved binary systems. We are interested in several kinds of binary stars: (1) detached WD+dM binaries such as NN Ser, QS Vir, and RR Cae (Qian et al 2009a(Qian et al , 2010b(Qian et al , 2012a; (2) subdwarf B-type (sdB) eclipsing binaries such as HS0705+6700 and NY Vir (e.g., Qian et al 2009cQian et al , 2012bQian et al , 2013; (3) magnetic CVs such as DP Leo (Qian et al 2010a); and (4) deeply eclipsing cataclysmic variables (CVs) including some nova-like CVs and dwarf novae (e.g., Qian et al 2009b). Here, we report the period variations of the eclipsing dwarf nova V2051 Oph obtained through photometric monitoring since 2008.…”

Searching for Spectroscopic Binaries Within Transition Disk Objects*

“…Using photometric data from Kepler, Doyle et al (2011) announced the first discovery of a circumbinary planet. Several other circumbinary planets have since been discovered (e.g., Orosz et al 2012;Qian et al 2012Qian et al , 2012bSchwamb et al 2013). These examples illustrate the need to further study multiple-star systems that host circumbinary material, and to test the effects of companion stars on disk dissipation and planet formation.…”