Apsidal Motion in Close Binaries with Variable Orbital Period

1974 ◽  
pp. 42-52
Author(s):  
Ioan Todoran
Keyword(s):  
Orbital Period ◽  
Close Binaries ◽  
Apsidal Motion

scholarly journals Eclipse timing variation of GK Vir: evidence of a possible Jupiter-like planet in a circumbinary orbit

2020 ◽  
Vol 497 (3) ◽  
pp. 4022-4029
Author(s):  
L A Almeida ◽  
E S Pereira ◽  
G M Borges ◽  
A Damineli ◽  
T A Michtchenko ◽  
...  
Keyword(s):  
Orbital Period ◽  
Binary Systems ◽  
Orbital Stability ◽  
Theoretical Description ◽  
Apsidal Motion ◽  
Variation Analysis ◽  
Third Body ◽  
Common Envelope ◽  
Cyclic Behaviour ◽  
Orbital Periods

ABSTRACT Eclipse timing variation analysis has become a powerful method to discover planets around binary systems. We applied this technique to investigate the eclipse times of GK Vir. This system is a post-common envelope binary with an orbital period of 8.26 h. Here, we present 10 new eclipse times obtained between 2013 and 2020. We calculated the O−C diagram using a linear ephemeris and verified a clear orbital period variation (OPV) with a cyclic behaviour. We investigated if this variation could be explained by the Applegate mechanism, the apsidal motion, or the light travel time (LTT) effect. We found that the Applegate mechanism would hardly explain the OPV with its current theoretical description. We obtained using different approaches that the apsidal motion is a less likely explanation than the LTT effect. We showed that the LTT effect with one circumbinary body is the most likely cause for the OPV, which was reinforced by the orbital stability of the third body. The LTT best solution provided an orbital period of ∼24 yr for the outer body. Under the assumption of coplanarity between the external body and the inner binary, we obtained a Jupiter-like planet around the GK Vir. In this scenario, the planet has one of the longest orbital periods, with a full observational baseline, discovered so far. However, as the observational baseline of GK Vir is smaller than twice the period found in the O−C diagram, the LTT solution must be taken as preliminary.

scholarly journals Cyclic Period Changes in the Algol WW Cygni

2004 ◽  
Vol 194 ◽  
pp. 87-88
Author(s):  
R. T. Zavala ◽  
B. J. McNamara ◽  
T. E. Harrison ◽  
H. Bogue ◽  
H. L. Maness
Keyword(s):  
Orbital Period ◽  
Period Change ◽  
Close Binaries ◽  
Cyclic Change ◽  
Optical Interferometer ◽  
Third Body ◽  
Magnetic Cycle ◽  
Color Changes ◽  
The Third ◽  
Algol System

AbstractYear to decade-long cyclic period changes have been observed in many classes of close binaries. The Algol binary WW Cygni shows a cyclic change in its orbital period with an amplitude of slightly more than 0.02 days and a period of 56 years. A hypothetical third or fourth body does not satisfactorily explain the observed variation in the orbital period. The change in luminosity and color of the system at primary eclipse minimum are in agreement with the model proposed by Applegate for a magnetic cycle induced period change in WW Cygni. We have commenced monitoring 9 close binaries for evidence of the luminosity and color changes consistent with the magnetic cycle hypothesis. δ Librae is suggested as a case suitable for observation with an optical interferometer to test the third body proposed for this Algol system.

A mechanism for orbital period modulation in close binaries

1992 ◽  
Vol 385 ◽  
pp. 621 ◽  
Author(s):  
James H. Applegate
Keyword(s):  
Orbital Period ◽  
Close Binaries

scholarly journals V346 Centauri: Early-type eclipsing binary with apsidal motion and abrupt change of orbital period

2016 ◽  
Vol 591 ◽  
pp. A129 ◽  
Author(s):  
Pavel Mayer ◽  
Petr Harmanec ◽  
Marek Wolf ◽  
Jana Nemravová ◽  
Andrej Prša ◽  
...  
Keyword(s):  
Orbital Period ◽  
Abrupt Change ◽  
Apsidal Motion ◽  
Early Type ◽  
Eclipsing Binary

scholarly journals Binary frequency among the O-type stars

1979 ◽  
Vol 83 ◽  
pp. 261-264
Author(s):  
Catharine D. Garmany
Keyword(s):  
Orbital Period ◽  
Selection Effect ◽  
Close Binaries ◽  
General Question ◽  
Mass Ratio ◽  
Double Line ◽  
Mass Ratios ◽  
Low Amplitude ◽  
Different Sources ◽  
Amplitude Versus

A great deal of work has been done on the theory of mass loss and evolution in close binaries, and numerous individual systems have been discussed in this connection, but the general question of the binary frequency of O-stars, and in particular, the initial binary mass ratio frequency or distribution of secondary masses, has not been completely answered. In general, we know that about half of all O-type stars are binaries; the most recent determination by Conti, Leep and Lorre (1977) found 58% of their sample to be certain or probable binaries. However, many of these stars were judged to be variable on the basis of only a few spectra from different sources, and therefore require further study. Another point to be examined concerns the binaries with available orbits: two thirds of these are double line systems. Figure 1 shows a plot of the semi-amplitude versus orbital period for all known systems, along with some theoretical curves for different mass ratios. Not only is the lack of single line systems obvious, but low amplitude systems are almost completely missing. This would appear to be only an observational selection effect, although it is to be noted that low amplitude double line Wolf-Rayet systems have been detected. If the effect is real, it implies that O-type binaries with mass ratios (m1/m2) greater than about three do not exist.

scholarly journals Secular period decreasing of 17 detached chromospherically active binaries

2008 ◽  
Vol 4 (S252) ◽  
pp. 437-438
Author(s):  
C. Q. Luo ◽  
Y. P. Luo ◽  
X. B. Zhang ◽  
L. C. Deng ◽  
Z. Q. Luo ◽  
...  
Keyword(s):  
Angular Momentum ◽  
Orbital Period ◽  
Close Binaries ◽  
Momentum Loss ◽  
System A ◽  
Angular Momentum Loss ◽  
Theoretical Predictions

AbstractThe long-term orbital period changes of detached chromospheric active binaries were surveyed. 17 of such systems are found to be undergoing secular period decreasing with the rates (dP/dt) of −3.05 × 10−9 to −3.77 × 10−5 days per year. The longer the orbital period, the more rapidly the period decreases. Following Stepien (1995), the period decreasing rate due to the angular momentum loss (AML) caused by magnetic wind is computed for each system. A comparison shows that the observed dP/dt's are obviously higher than that of the theoretical predictions by 1-3 orders of magnitude. It suggests that the magnetic wind is not likely the determinant mechanism driving the AML in close binaries.

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