The W-subtype active contact binary PZ UMa with a possible more massive tertiary component

Xiao, Zhi Yu; Soonthornthum, Boonrucksar

doi:10.1093/pasj/psz003

Cited by 30 publications

(7 citation statements)

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“…The more massive component in a binary system expanded first and filled its critical Roche lobe, and then transfer masses to the less massive companion star through the inner Lagrangian point of the binary system. In recent years, more and more contact binaries were reported to have additional components orbiting around the central binaries (Yang et al 2019;Zhou & Soonthornthum 2019;Zhang et al 2020). The additional components may be ejected from the center of initially multiple star system and pump out angular momentum from the multiple star system, and left out a tight binary system, which will evolve to a contact binary system finally, especially for the formation of M-type contact binaries (Goodwin et al 2004;Qian et al 2015).…”

Section: Discussionmentioning

confidence: 99%

Orbital period correction and light curve modeling of the W-subtype shallow contact binary OWLeo

Zhou,

Qian

2020

Preprint

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Orbital period and multi-color light curves' investigation of OW Leo are presented for the first time. The orbital period of OW Leo is corrected from P = 0.325545 days to P = 0.32554052 days in our work, and the observational data from the All-Sky Automated Survey for SuperNovae (ASAS-SN) are used to test the newly determined orbital period. Then, the phased light curves are calculated with the new period and the Wilson-Devinney program is applied to model the light curves, which reveal that OW Leo is a W-subtype shallow contact binary system (q = 3.05, f = 12.8 %). The absolute physical parameters of the two component stars are estimated to be MThe evolutionary status show that the more massive star is less evolved than the less massive star. OW Leo has very low metal abundance, which means its formation and evolution are hardly influenced by any additional component. It is formed from an initially detached binary systems through nuclear evolution and angular momentum loss via magnetic braking, and have passed a very long time of main sequence evolution.

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Section: Discussionmentioning

confidence: 99%

Orbital period correction and light curve modeling of the W-subtype shallow contact binary OWLeo

Zhou,

Qian

2020

Preprint

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“…But YZ Phe shows a large hot spot (> 50 deg) in Figure 9 which differs from those systems and its spot is likely to grow from 54 deg (Sameg & Terrell 1995) to 89 deg. The big spotted area can be formed from many groups of small spots (Suarez Mascareno et al 2016) and each spot can vary with time, but some spots may stay for long timescale without changing e.g., CSTAR 038663 (Qian et al 2014) and PZ UMa (Zhou & Soonthornthum 2019). This may suggest that spots and magnetic activities in contact systems are complex and the mechanism or physical processes behind the large hot spot in YZ Phe is unknown.…”

Section: Discussionmentioning

confidence: 99%

YZ Phe: an active contact binary with variation of the O'Connell effect and orbital period change

Sarotsakulchai,

Qian,

Soonthornthum

et al. 2019

Preprint

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YZ Phe is a very short-period contact binary (Sp.= K2 V) with an orbital period of 0.2347 days near the short period limit (0.22 d). We present the complete light curves in V RI bands, which photometric data were obtained with the 0.61-m reflector of PROMPT-8 at CTIO in Chile during June to October 2016 and August 2017. The photometric solutions were determined by using the W-D method and the results reveal that YZ Phe is a W-subtype shallow contact binary (f ∼ 10%, q = 2.635 or 1/q = 0.379 for W subtype) with rotational motion of a large hot spot on the more massive component, showing a strong O'Connell effect with variation of maxima in photometric time series at period of 4.20 yr and stellar cycle at period of 1.28 yr. By compiling all available eclipse times, the result shows a long-term period decrease at a rate of dP/dt = −2.64(±0.02) × 10 −8 d yr −1 , superimposed on a cyclic variation (A 3 = 0.0081 days and P 3 = 40.76 years). This variation cannot be explained by Applegate mechanism. Thus, the cyclic change may be interpreted as light-travel time effect via the presence of a cool third body. Based on photometric solutions, the third light was detected with 2% of total light in V and I bands. Those support the existence of a third body. For the long-term period decrease, it can be explained by mass transfer from the more massive component (M 2 ∼ 0.74M ⊙ ) to the less massive one (M 1 ∼ 0.28M ⊙ ) or plus AML via magnetic braking. With 1/q < 0.4 and long-term period decrease, all suggest that YZ Phe is on the AML-controlled state and its fill-out factor will increase, as well as the system will evolve into a deeper normal contact binary.

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“…All the orbits of systems were considered to be circular in this work. The q-search method was used to determine the preliminary mass ratio (see e.g., Zhang & Qian 2013;Zhou & Soonthornthum 2019;Liu et al 2020;Li et al 2022b). Through this method, suitable solutions were detected from a series of convergent solutions for different mass ratios.…”

Section: Photometric Investigations With the W-d Methodsmentioning

confidence: 99%

A Study of Ten Early-type Contact Binary Stars in the Small Magellanic Cloud

Chu-Qi,

Fu-Xing,

Sheng-Bang

et al. 2023

PASP

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To study early-type binary systems in different evolutionary stages or environments, the Small Magellanic Cloud (SMC) is an ideal laboratory due to its low metallicity compared to that of the Milky Way. We conduct a study on the period changes of the close binary systems with B-type spectral classifications in the SMC using OGLE collections. Ten B-type binaries that show no significant periodic variations based on the current observational data were analyzed. Through O − C analysis, four of the ten early-type binaries show a long-term period decrease, one shows a long-term period increase, and the other five systems are ambiguous due to the limitations of the observational data. Among the period-decreasing systems, two may be mainly caused by mass transfer, while the rest may be caused by angular momentum loss. The Wilson-Devinney code (W-D method) is used to analyze their I-band photometric light curves. According to the W-D results, five early-type binaries are in the deep contact state, three are in the shallow contact state, while two are in the medium contact state, and the temperature ratios of these early-type binaries are all close to unity. The five deep contact binaries are highly unstable systems and therefore serve as important objects for the study of binary mergers. Finally, a discussion on the evolution of early-type binary stars is conducted by combining the analyses of the light curves and the periodic changes of ten early-type binaries, that implies that the majority of early-type binaries in the SMC may form contact binaries from a phase of rapid mass transfer.

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The W-subtype active contact binary PZ UMa with a possible more massive tertiary component

Cited by 30 publications

References 50 publications

Orbital period correction and light curve modeling of the W-subtype shallow contact binary OWLeo

Orbital period correction and light curve modeling of the W-subtype shallow contact binary OWLeo

YZ Phe: an active contact binary with variation of the O'Connell effect and orbital period change

A Study of Ten Early-type Contact Binary Stars in the Small Magellanic Cloud

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