Period Changes of AO Camelopardalis and AM Leonis and Their Implications for the Presence of Tertiary Components and the Evolutionary States of the Two Overcontact Binary Systems

Qian, S.‐B.; He, Jiajia; Fang, Xiang; Ding, Xigui; Soonthornthum, Boonrucksar

doi:10.1086/427852

Cited by 21 publications

(7 citation statements)

References 27 publications

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“…The sinusoidal term suggests the existence of a periodic oscillation with an amplitude of 0.053 d. Using w = 360° P e / T , the period, T , of this oscillation was determined to be 86.6 yr, where P e is the orbital period of GW Tau in years and w is the coefficient of E in the fit. This type of period variation also appears in many other close binaries, such as AG Vir (Qian 2001), XZ CMi (Qian 2002a), BO Peg (Qian 2002b), IR Cas (Zhu, Qian & Xiang 2004), AO Cam (Qian et al 2005a) and PP Lac (Qian, Zhu & Boonruksar 2005b).…”

Section: Orbital Period Study Of Bl and And Gw Taumentioning

confidence: 60%

BL Andromedae and GW Tauri: close binary stars in a key evolutionary stage

Zhu

Qian

2006

Monthly Notices of the Royal Astronomical Society

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A photoelectric light curve of BL And is presented along with the first CCD light curve of GW Tau. Both objects are short‐period eclipsing binaries and were observed in 2003 or 2004. Photometric elements were computed using the latest version of the Wilson–Van Hamme code. The results reveal that BL And is a semidetached system with the primary component filling its Roche lobe and the secondary one almost filling but still detached, while GW Tau is a marginal‐contact binary system with a small degree of contact (f= 10.9 per cent) and a large temperature difference of about 3100 K. All available eclipse times, including new ones, were analysed for each system. It was found that the orbital period of BL And is decreasing at the rate of dP/dt=−2.36 × 10−8 (±0.09) d yr−1 while that of GW Tau may be decreasing or oscillating. We think period decrease is more probable. The derived configuration and secular period decrease for BL And combined with the asymmetry of the light curve indicate that this system may evolve from the present semidetached phase into a contact stage, with mass transfer from the primary component to the secondary one through the L1 point, or that it might just undergo the broken stage predicted by the theory of thermal relaxation oscillations. In contrast, GW Tau is a marginal‐contact binary in poor thermal contact and may be at the beginning of the contact phase.

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Section: Orbital Period Study Of Bl and And Gw Taumentioning

confidence: 60%

BL Andromedae and GW Tauri: close binary stars in a key evolutionary stage

Zhu

Qian

2006

Monthly Notices of the Royal Astronomical Society

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“…1 along with the observed values. The parameters of light-time curves obtained by Qian et al (2005), Albayrak et al (2005a) and obtained by us are given in Table 2. Designations in the first column of Table 2 correspond to following parameters: N is the total number of the moments of minima under consideration, (O − C LT C ) 2 is the value of the minimum sum of the squares of the residuals of O-C differences from the light-time curve, JD ⊙ I min and P orb are reference epochs for the primary minimum and the true period of the AM Leo respectively, a sin i, e, w, T 0 and P 12 are the semi-major axis, inclination, eccentricity, longitude and epoch of the periastron passage and the period of the orbit of the eclipsing pair around the mass center of the AM Leo system with the third body, respectively.…”

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confidence: 86%

“…This hypothesis was first suggested by Demircan & Derman (1992). Later Albayrak et al (2005a) and Qian et al (2005) have determined the parameters of the light-time curve based on the analysis of the moments of minima from data obtained using photomultiplier and CCD detectors only. Albayrak et al (2005a) obtained the mutual orbital period of AM Leo and the third body by the very eccentric orbit to be about 45 years, they also estimated the mass of the third body to be M 3 = 0.18M ⊙ .…”

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confidence: 99%

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New Light-Time Curve of Eclipsing Binary AM Leo

Gorda¹,

Matveeva²

2017

IBVS

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The eclipsing variable star AM Leo (BD +10• 2234 A) is a bright component (V = 9.1− 9.7 mag) of the visual binary system ADS 8024 (ρ = 11′′ .4, θ = 270 • ) (Hiller et al. 2004). The most comprehensive survey of the photometric observations of AM Leo were given in the studies of Hiller et al. (2004) and Albayrak et al. (2005a). Many authors noted temporal variations in the light curve of AM Leo. Along with the light curve variations, orbital variations have been observed too. Various hypotheses were proposed to explain this phenomenon. The most likely reason for the period change in AM Leo is now considered to be the presence of a third body in the system. This hypothesis was first suggested by Demircan & Derman (1992) The CCD observations data were reduced using the MaxImDL and Muniwin (http://cmunipack.sourceforge.net) packages. The minima time were computed by a parabola fitting method and averaged from all filters used during the night. Values of the moments of

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“…Zhu et al 2010Zhu et al , 2012Mikulášek et al 2012a), the presence and characteristics of possible invisible bodies (stars, planets, e.g. Van Hamme & Wilson 2007;Qian et al 2005) in the system, or the degree of the mass concentration in stellar interiors (internal structure constants) if we study apsidal motion in some eccentric EBs (e.g. Kopal 1978;Claret & Gimenénez 1993;Zasche & Wolf 2013).…”

Section: Introductionmentioning

confidence: 99%

Phenomenological modelling of eclipsing system light curves

Mikulášek¹

2015

A&A

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Context. The observed light curves of most eclipsing binaries and stars with transiting planets can be described well and interpreted by current advanced physical models that also allow for determining many of the physical parameters of eclipsing systems. However, for several common practical tasks, there is no need to know the detailed physics of a variable star, but only the shapes of their light curves or other phase curves.Aims. We present a set of phenomenological models for the light curves of eclipsing systems. Methods. We express the observed light curves of eclipsing binaries and stars, which are transited by their exoplanets orbiting in circular trajectories, by a sum of special, analytical, few-parameter functions that enable fitting their light curves with an accuracy of better than 1%. The proposed set of phenomenological models of eclipsing variable light curves were then tested on several real systems. For XY Bootis, we also give a detailed comparison of the results obtained using our phenomenological modelling with those found using available physical models. Results. We demonstrate that the proposed phenomenological models of transiting exoplanet and eclipsing binary light curves applied to ground-based photometric observations yield results compatible with those obtained by applying more complex physical models. Conclusions. The suggested phenomenological modelling appears useful for solving a number of common tasks in the field of eclipsing variable research.

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Period Changes of AO Camelopardalis and AM Leonis and Their Implications for the Presence of Tertiary Components and the Evolutionary States of the Two Overcontact Binary Systems

Cited by 21 publications

References 27 publications

BL Andromedae and GW Tauri: close binary stars in a key evolutionary stage

BL Andromedae and GW Tauri: close binary stars in a key evolutionary stage

New Light-Time Curve of Eclipsing Binary AM Leo

Phenomenological modelling of eclipsing system light curves

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