A photometric study of the W UMa-type system U Pegasi

Djurašević, G.; Rovithis‐Livaniou, H.; Rovithis, P.; Erkapić, S.; Milovanović, N.

doi:10.1051/0004-6361:20000493

Cited by 15 publications

(10 citation statements)

References 20 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“… References: (1) Gazeas et al (2005); (2) Zoła et al (2005); (3) Gazeas & Niarchos (2006); (4) Terrell et al (2006);(5) Yang, Qian & Zhu (2005); (6) Zhang & Zhang (2004); (7) Yakut et al (2005); (8) Qian et al (2005); (9) Lu, Hrivnak & Rush (2007), (10) Szalai et al (2007); (11) Lu (1991); (12) Zhang, Zhang & Deng (2005); (13) Özdemir et al (2002); (14) Djurašević et al (2001). …”

Section: Status Of W Uma Systemsmentioning

confidence: 99%

The evolutionary status of W Ursae Majoris-type systems

Zhang

Han

et al. 2008

Monthly Notices RAS

View full text Add to dashboard Cite

Well-determined physical parameters of 130 W UMa systems have been collected from the literature. Based on these data, the evolutionary status and dynamical evolution of W UMa systems are investigated. It is found that there is no evolutionary difference between W- and A-type systems in $M-J$ diagram which is consistent with the results derived from the analysis of observed spectral type, $M-R$ and $M-L$ diagrams of W UMa systems. $M-R$ and $M-L$ diagrams of W- and A-type systems indicate that a large amount of energy should be transferred from the more massive to the less massive component so that they are not in thermal equilibrium and undergo thermal relaxation oscillation (TRO). Meanwhile, the distribution of angular momentum, together with the distribution of mass ratio, suggests that the mass ratio of the observed W UMa systems is decreased with the decrease of their total mass. This could be the result of the dynamical evolution of W UMa systems which suffer angular momentum loss (AML) and mass loss due to magnetic stellar wind (MSW). Consequently, the tidal instability forces these systems towards the lower q values and finally to fast rotating single stars.Comment: 8 pages, 5 figures, accepted for publication in MNRA

show abstract

Section: Status Of W Uma Systemsmentioning

confidence: 99%

The evolutionary status of W Ursae Majoris-type systems

Zhang

Han

et al. 2008

Monthly Notices RAS

View full text Add to dashboard Cite

show abstract

“…In a recent study, Djurašević et al (2001) investigated the long term photometric variations of the system over the time interval of 1950 to 1989. They concluded that the complex variations of the light-curves during these four decades can be explained by the variable spot activity of the cooler component.…”

Section: U Pegasimentioning

confidence: 99%

Indirect evidence for short period magnetic cycles in W UMa stars

Borkovits¹,

Elkhateeb

Csizmadia

et al. 2005

A&A

View full text Add to dashboard Cite

Complex period variations of five W UMa type binaries (AB And, OO Aql, DK Cyg, V566 Oph, U Peg) were investigated by analyzing their O−C diagrams, and several common features were found. Four of the five systems show secular period variations at a constant rate on the order of |Ṗ sec /P| ∼ 10 −7 yr −1 . In the case of AB And, OO Aql, and U Peg a high-amplitude, nearly one-century long quasi-sinusoidal pattern was also found. It might be explained as light-time effect, or by some magnetic phenomena, although the mathematical, and consequently the physical, parameters of these fits are very problematic, as the obtained periods are very close to the length of the total data range. The most interesting feature of the studied O−C diagrams is a low amplitude (∼2−4 × 10 −3 d) modulation with a period around 18-20 yr in four of the five cases. This phenomenon might be indirect evidence of some magnetic cycle in late-type overcontact binaries as an analog to the observed activity cycles in RS CVn systems.

show abstract

“…In fact, spot activity derived from the light curves of several observing seasons and the corresponding magnetic activity also appear in many other W UMa binary stars, such as AU Ser (Gürol 2005), U Peg (Djurašević et al 2001), AD Cnc (Qian et al 2007), FG Hya (Qian & Yang 2005) and CE Leo (Yang & Liu 2002b).…”

Section: Discussionmentioning

confidence: 91%

Variation of the period and light curves of the solar-type contact binary EQ Tauri

Yuan

Qian

2007

Monthly Notices of the Royal Astronomical Society

View full text Add to dashboard Cite

We present two new sets of complete light curves of EQ Tauri (EQ Tau) observed in 2000 October and 2004 December. These were analysed, together with the light curves obtained by Yang & Liu in 2001 December, with the 2003 version of the Wilson-Devinney code. In the three observing seasons, the light curves show a noticeable variation in the time-scale of years.The more massive component of EQ Tau is a solar-type star (G2) with a very deep convective envelope, which rotates about 80 times as fast as the Sun. Therefore, the change can be explained by dark-spot activity on the common convective envelope. The assumed unperturbed part of the light curve and the radial velocities published by Rucinski et al. were used to determine the basic parameters of the system, which were kept fixed for spot modelling in the three sets of light curves. The results reveal that the total spotted area on the more massive component covers 18, 3 and 20 per cent of the photospheric surface in the three observing seasons, respectively. Polar spots and high-latitude spots are found. The analysis of the orbital period has demonstrated that it undergoes cyclical oscillation, which is due to either a tertiary component or periodic magnetic activity in the more massive component.

show abstract

A photometric study of the W UMa-type system U Pegasi

Cited by 15 publications

References 20 publications

The evolutionary status of W Ursae Majoris-type systems

The evolutionary status of W Ursae Majoris-type systems

Indirect evidence for short period magnetic cycles in W UMa stars

Variation of the period and light curves of the solar-type contact binary EQ Tauri

Contact Info

Product

Resources

About