Is There a Substellar Object Orbiting the Solar-like Stable Contact Binary V2284 Cyg?

Abstract

V2284 Cyg is a neglected W UMa-type binary star for photometric investigations. Monitored by the Kepler Space Telescope from 2009 to 2013, its light curves are continuously stable, suggesting that both components are inactive during this time interval. Based on the short-cadence observations, we determined the photometric solutions by using the 2013 version of the Wilson-Devinney code. These parameters reveal that V2284 Cyg is a W-type system with a degree of contact factor of f=39.23% and a mass ratio of q=2.90. Meanwhile, hundreds of times of minimum light were obtained and applied to analyze the orbital period changes. In the O-C diagram, a smallamplitude cyclic oscillation (A 3 =0.00030 days and T 3 =2.06 years) superimposed on a secular decreasing was found. The continuous decreasing may be a result from the mass transfer from the more massive component to the less massive one. With the long-term decreasing of the orbital period, this binary will evolve into a deeper contact system. Because the light curve is stable, the cyclic variation is plausibly explained as the light-travel time effect (LTTE) due to the presence of an additional body. The mass of the companion is. If the orbital plane inclination is a random distribution, it is a brown dwarf with 66.7% probability. Therefore, the companion of V2284 Cyg is possibly the first candidate of the brown dwarf orbiting around contact binary, where both component are sharing a common convective envelope.

RW Doradus: A solar-type shallow contact binary with a new orbital period investigation

“…However, almost contact binaries were found to be a triple or multiple system (Pribulla & Rucinski 2006;D'Angelo et al 2006;Rucinski et al 2007), and one can see from table 6 that most of them have no third light in their light curves but show periodic variations in long-term period changes. Recently, a possible substellar object orbiting the solar-like contact binary V2284 Cyg was first reported by Wang et al (2017), and also in the K-type shallow contact binary CC Com with very low mass M 3 = 0.066 M by Yang et al (2009a), and KIC 9532219 with M 3 = 0.089 M by Lee et al (2016) or TX Cnc with M 3 = 0.097 M by Liu et al (2007). More recently, the eclipsing binary Kepler-503 has been found to be a brown dwarf or low-mass star with M 3 = 0.075 M orbiting around a subgiant star (Cañas et al 2018).…”

Photometric Study of Two Totally Eclipsing Contact Binaries: V789 Her and V1007 Cas

“…As proposed byLiao & Qian (2010), the most plausible reason for the cyclic variation in the orbital period of binaries is the light travel time effect via a distant third companion. The presence of a tertiary star is very common in contact binaries, such as EP And(Lee et al 2013), SDSS J001641-000925(Qian et al 2015), and V2284 Cyg(Wang et al 2017). The mass function f (m)=6.06(±0.35)×10 −1 M e was obtained according the following formula:…”

RW Dor: A G-type shallow contact binary with new orbital period investigation

“…However, almost contact binaries were found to be triple or multiple systems (Pribulla & Rucinski 2006;D'Angelo et al 2006;) and one can see at Table 6, most of them have no third light in their light curves but show periodic variations in longterm period changes. Recently, a possible substellar object orbiting around the solar-like contact binary V2284 Cyg was firstly reported by Wang et al (2017). Also in K-type shallow contact binary CC Com with very low mass M 3 = 0.066M ⊙ by and KIC 9532219 with M 3 = 0.089M ⊙ by Lee at el.…”