Mass transfer and possible third-body effect on the period variations of the near-contact binary CN And

Cai, J. T.; Yu, Yun-Xia; Hu, Ke; Fang, Xiang

doi:10.1088/1674-4527/19/8/106

Cited by 3 publications

(1 citation statement)

References 31 publications

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“…505 Cyg is a progenitor of an overcontact binary. Now, it may lie in the broken-contact stage predicted by the TRO theory like UU Lyn (Zhu et al 2007), BL And, GW Tau ), V473 Cas, II Per (Zhu et al 2009), IR Cas (Li et al 2014), IZ Mon (Yang et al 2016), CN And (Cai et al 2019), NSVS 5066754 (Samec et al 2016) and DD Com (Zhu et al 2010). As pointed out by the TRO theory, W UMa binaries must go through oscillations about the state of marginal contact.…”

Section: Discussionmentioning

confidence: 93%

V505 Cyg: A Mass-transferring Marginal Contact Binary

Chang¹,

Zhu²

2022

PASP

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High-precision photometric data of V505 Cyg from TESS and one spectrum observed by us are presented in this work, and the stellar atmospheric parameters of the primary component were derived via spectral fitting. Applying the Wilson–Devinney code, the photometric elements were computed for the first time. The results show V505 Cyg is a near contact binary with the primary filling its Roche Lobe and the secondary a little under-filling, along with the temperature difference of about ΔT = 1900 K between the two components. The eclipse is total and lasts for about 90 minutes, which is about 0.1 phase, so the photometric results are reliable. This system belongs to near-contact binaries with the light curves enhanced around the left shoulder of the secondary minimum, which can be explained by a hot spot on the secondary components due to mass transfer, via a stream from the primary components hitting the facing surface of the secondary components. Meanwhile, we conducted an orbital period investigation of it in detail. The orbital period study based on all times of minimum including 230 new ones determined by us reveals a secular period decreasing at the rate of dP/dt = −2.31 × 10−7 d · yr−1. The decrease of the orbital period can be the result of mass transfer between the components, agreeing well with the configuration and the asymmetric light curves of V505 Cyg. V505 Cyg is therefore another rare example of mass transferring marginal contact binary lying on the rapid evolutionary stage predicted by the Thermal Relaxation Oscillation theory. With the orbital period decrease, V505 Cyg will evolve into an overcontact binary.

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Section: Discussionmentioning

confidence: 93%

V505 Cyg: A Mass-transferring Marginal Contact Binary

Chang¹,

Zhu²

2022

PASP

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Investigation on the mass transferring near-contact binary TT Cet

Xiao-man

Chang²

2020

Publ. Astron. Soc. Aust.

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First multi-colour complete light curves and low-resolution spectra of short-period eclipsing binary TT Cet are presented. The stellar atmospheric parameters of the primary star were derived through spectra fitting as: $T_{eff}=7\,091\pm124\,{\text{K}}$ , $\log g = 4.15\pm0.33\,{\text{cm}}/\text{s}^2$ , and $[Fe/H]=-0.23\pm0.04\,\text{dex}$ . The light curves were analysed using the Wilson–Devinney code. The photometric solution suggests that this target should be a near-contact binary with the primary component filling its critical Roche lobe (i.e. SD1-type NCB). The luminosity enhancement around the primary light maximum (phase 0.10–0.40) on the light curve was detected like other SD1-type NCBs, which could be caused by a hot spot near the facing surface of the secondary component due to mass transfer. Long-term decrease of the orbital period at a rate of $dP/dt=-5.01\,({\pm}0.06)\times 10^{-8}\,{{\text{d}} \cdot{yr}}^{-1}$ was detected by the O–C analysis, which supports the mass transfer from the primary to the secondary and is consistent with its primary filling configuration. No third body was found through the light curve and O–C analysis. TT Cet may locate in the broken contact stage predicted by the thermal relaxation oscillation theory (TRO) and will evolve to the contact stage eventually. It is another good observational example supporting the TRO theory. We have collected all known SD1-type NCBs with absolute parameters from the literatures. The relations of these parameters are summarised for these rare systems.

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Contact binaries at different evolutionary stages

Qian

Zhu

Liu

et al. 2020

Res. Astron. Astrophys.

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Contact binaries consist of two strongly interacting component stars where they are filling their critical Roche lobes and sharing a common envelope. Most of them are main-sequence stars, but some of them are post main-sequence systems. They are good astrophysical laboratories for studying several problems such as the merging of binary stars, evolution of the common envelope, the origin of luminous red nova outbursts and the formation of rapidly rotating single stars with possible planetary systems. A large number of contact binary candidates were detected by several photometric surveys around the world and many of them were observed by the LAMOST spectroscopic survey. Based on follow-up observations, the evolutionary states and geometrical structures of some systems were understood well. In this review, we will introduce and catalog new stellar atmospheric parameters (i.e., the effective temperature (T eff), the gravitational acceleration (log(g)), metallicity ([Fe/H]) and radial velocity (Vr )) for 9149 EW-type contact binaries that were obtained based on low- and medium-resolution spectroscopic surveys of LAMOST. Then we will focus on several groups of contact binary stars, i.e., marginal contact binary systems, deep and low-mass ratio contact binary stars, binary systems below the short-period limit of contact binaries and evolved contact binaries. Marginal contact binaries are at the beginning of the contact stage, while deep and low-mass ratio contact binary stars are at the final evolutionary stage of tidally locked binaries. Several statistical relations including the period-temperature relation are determined well by applying LAMOST data and their formation and evolutionary states are reviewed. The period-color relation of M-type binaries reveals that there are contact binaries below the short-period limit. Searching for and investigating contact binaries near and below this limit will help us to understand the formation of contact binary systems and a new prediction for the short-period limit is about 0.15 d. Some evolved contact binaries were detected by the LAMOST survey where both components are sub-giants or giants. They provide a good opportunity to investigate evolution of the common envelope and are the progenitors of luminous red novae like V1309 Sco.

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Mass transfer and possible third-body effect on the period variations of the near-contact binary CN And

Cited by 3 publications

References 31 publications

V505 Cyg: A Mass-transferring Marginal Contact Binary

V505 Cyg: A Mass-transferring Marginal Contact Binary

Investigation on the mass transferring near-contact binary TT Cet

Contact binaries at different evolutionary stages

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