scholarly journals First photometric analysis of magnetic activity and orbital period variations for the semi-detached binary BU Vulpeculae

2018 ◽  
Vol 70 (4) ◽  
Author(s):  
Jingjing Wang ◽  
Bin Zhang ◽  
Jing Yu ◽  
Liang Liu ◽  
Xiaoman Tian
Keyword(s):  
Orbital Period ◽  
Magnetic Activity ◽  
Photometric Analysis ◽  
Period Variations

scholarly journals Applegate mechanism in post-common-envelope binaries: Investigating the role of rotation

2018 ◽  
Vol 615 ◽  
pp. A81 ◽  
Author(s):  
F. H. Navarrete ◽  
D. R. G. Schleicher ◽  
J. Zamponi Fuentealba ◽  
M. Völschow
Keyword(s):  
Orbital Period ◽  
Rotation Rate ◽  
Main Sequence ◽  
Magnetic Activity ◽  
Main Sequence Star ◽  
Common Envelope ◽  
Rotation Rates ◽  
Critical Rotation ◽  
Period Variations ◽  
Time Variations

Context. Eclipsing time variations are observed in many close binary systems. In particular, for several post-common-envelope binaries (PCEBs) that consist of a white dwarf and a main sequence star, the observed-minus-calculated (O–C) diagram suggests that real or apparent orbital period variations are driven by Jupiter-mass planets or as a result of magnetic activity, the so-called Applegate mechanism. The latter explains orbital period variations as a result of changes in the stellar quadrupole moment due to magnetic activity. Aims. In this work we explore the feasibility of driving eclipsing time variations via the Applegate mechanism for a sample of PCEB systems, including a range of different rotation rates. Methods. We used the MESA code to evolve 12 stars with different masses and rotation rates. We applied simple dynamo models to their radial profiles to investigate the scale at which the predicted activity cycle matches the observed modulation period, and quantifiy the uncertainty. We further calculated the required energies to drive the Applegate mechanism. Results. We show that the Applegate mechanism is energetically feasible in 5 PCEB systems. In RX J2130.6+4710, it may be feasible as well considering the uncertainties. We note that these are the systems with the highest rotation rate compared to the critical rotation rate of the main-sequence star. Conclusions. The results suggest that the ratio of physical to critical rotation rate in the main sequence star is an important indicator for the feasibility of Applegate’s mechanism, but exploring larger samples will be necessary to probe this hypothesis.

Orbital-Period Variations and Photometric Analysis for the Neglected Contact Binary EH Cancri

2011 ◽  
Vol 123 (906) ◽  
pp. 895-902 ◽  
Author(s):  
Y.-G. Yang ◽  
Z.-Y. Shao ◽  
H.-J. Pan ◽  
X.-G. Yin
Keyword(s):  
Orbital Period ◽  
Photometric Analysis ◽  
Period Variations ◽  
Contact Binary

Orbital period variations of two W UMa-type binaries: UY UMa and EF Boo

New Astronomy ◽  
2017 ◽  
Vol 55 ◽  
pp. 13-16 ◽  
Author(s):  
Yun-Xia Yu ◽  
Xu-Dong Zhang ◽  
Ke Hu ◽  
Fu-Yuan Xiang
Keyword(s):  
Orbital Period ◽  
Period Variations

scholarly journals Two bodies with high eccentricity around the cataclysmic variable QS Vir

2010 ◽  
Vol 6 (S276) ◽  
pp. 495-496 ◽  
Author(s):  
Leonardo A. Almeida ◽  
Francisco Jablonski
Keyword(s):  
Orbital Period ◽  
Giant Planet ◽  
Cataclysmic Variable ◽  
Brown Dwarf ◽  
Period Variations ◽  
Angular Momentum Loss ◽  
Best Fitting ◽  
Orbital Periods ◽  
The Masses ◽  
Two Bodies

AbstractQS Vir is an eclipsing cataclysmic variable with 3.618 hrs orbital period. This system has the interesting characteristics that it does not show mass transfer between the components through the L1 Lagrangian point and shows a complex orbital period variation history. Qian et al. (2010) associated the orbital period variations to the presence of a giant planet in the system plus angular momentum loss via magnetic braking. Parsons et al. (2010) obtained new eclipse timings and observed that the orbital period variations associated to a hypothetical giant planet disagree with their measurements and concluded that the decrease in orbital period is part of a cyclic variation with period ~16 yrs. In this work, we present 28 new eclipse timings of QS Vir and suggest that the orbital period variations can be explained by a model with two circumbinary bodies. The best fitting gives the lower limit to the masses M1 sin(i) ~ 0.0086 M⊙ and M2 sin(i) ~ 0.054 M⊙; orbital periods P1 ~ 14.4 yrs and P2 ~ 16.99 yrs, and eccentricities e1 ~ 0.62 and e2~0.92 for the two external bodies. Under the assumption of coplanarity among the two external bodies and the inner binary, we obtain a giant planet with ~0.009 M⊙ and a brown dwarf with ~ 0.056 M⊙ around the eclipsing binary QS Vir.

An Investigation of the Physical Mechanisms of Orbital Period Variations of the Semidetached Binary UW Vir

2009 ◽  
Vol 33 (3) ◽  
pp. 279-286 ◽  
Author(s):  
Jia Zhang ◽  
Sheng-Bang Qian ◽  
Soonthornthum Boonrucksar
Keyword(s):  
Orbital Period ◽  
Physical Mechanisms ◽  
Period Variations

scholarly journals Long-Term Orbital Period Variations for EU Hydrae

2003 ◽  
Vol 55 (2) ◽  
pp. 499-502 ◽  
Author(s):  
Sheng-Bang Qian ◽  
Soonthornthum Boonrucksar
Keyword(s):  
Orbital Period ◽  
Period Variations
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