Masses and angular momenta of contact binary stars

Gazeas, K.; Niarchos, P. G.

doi:10.1111/j.1745-3933.2006.00182.x

Cited by 62 publications

(71 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Numerous predictions suggested that contact binaries should evolve toward diminishing mass ratios until a total merger the components and dissolution of secondaries [6,46]. This would also agree with the surprising similarity of secondary masses in contact binaries seen by Gazeas and Niarchos [47,53]. If the two sequences in Figure 2 correspond to the respective detached (the upper sequence) and contact configurations (the lower sequence), some systems in the upper sequence must be misclassified as EW's and EB's.…”

Section: Spectroscopy: the Ddo Programsupporting

confidence: 54%

Contact Binaries: The Current State

Ruciński¹

2010

AIP Conference Proceedings

View full text Add to dashboard Cite

Lucy's model of contact binaries has been serving well since its development in 1968 as an excellent conceptual framework for internal structure and evolution studies of the W UMa type stars. Its over-constrained structural demands were recognized early, but -from the observational point of view -it was particularly appealing in its ability to explain W UMa-type binary light curves. Large numbers of photometric light curves of W UMa type binaries have been solved for geometrical parameters utilizing the clarity and simplicity of Lucy's model to the point of frequent over-interpretation of the meager lightcurve information content. Many, single, photometric solutions do not translate into a satisfactory understanding of these binaries. As the David Dunlap Observatory radial velocity program of bright, close binary stars (conducted in the last 10 years before the observatory closure in 2008) has shown, there are problems when spectroscopic results are confronted with light-curve solutions: Very frequently, the crucial parameter of the mass-ratio determined spectroscopically is entirely different from its photometric analogue (i.e. the one determined assuming a strict adherence to the Lucy's model), the third star incidence is high (which makes light curve solutions difficult, if not entirely wrong, even for totally eclipsing systems) and -last but not least -the model has serious difficulties for the best observed case of the crucially important, very low mass-ratio system AW UMa. One would argue that it is spectroscopy which gives correct results, but it requires access to large telescopes, extensive use of special techniques to analyze strongly blended and rotationally broadened spectra and is simply much harder to do than photometry. If the light curve solutions deceive us into believing in correctness of Lucy's contact-binary model and if only a fraction of (or none among) W UMa systems can be explained by that model, then the subject of contact binaries needs new ideas and new, mostly spectroscopic, high quality observations.

show abstract

Section: Spectroscopy: the Ddo Programsupporting

confidence: 54%

Contact Binaries: The Current State

Ruciński¹

2010

AIP Conference Proceedings

View full text Add to dashboard Cite

show abstract

“…Observations show that there are several low mass contact binaries (LMCB) with the total mass close to 1-1.4 M (Gazeas & Niarchos 2006, Gazeas & Stȩpień 2008. The LMCB compared with our models include the first 9 stars from Table 1 of Gazeas & Stȩpień (2008).…”

Section: Evolution Of Contact Binaries and The Suggested New Modelmentioning

confidence: 99%

The Evolution of Low Mass Contact Binaries

Stępień

Gazeas

2011

Proc. IAU

View full text Add to dashboard Cite

show abstract

“…In our study we consider component "1" as the presently more massive one. Our assumption is based on the double-lined spectroscopic observations, where the mass ratio is taken as q = M 2 /M 1 ≤ 1.As shown also by Gazeas & Niarchos (2006), the plots of mass and angular momentum versus orbital period gave a direct evidence of evolution into contact, as well as the evolution of A-type W UMa binaries towards the W-type. Figure 1 (upper panel) shows a plot of mass versus orbital period, as well as the equivalent plots of radius and luminosity in logarithmic scale.…”

mentioning

confidence: 90%

Physical parameters of contact binaries through 2-D and 3-D correlation diagrams

Gazeas¹

2009

cia

View full text Add to dashboard Cite

Physical parameters of contact binaries are studied through 2-D and 3-D correlations among them. It is shown that the physical parameters (i.e. mass, radius and luminosity) are closely correlated with the orbital period and mass ratio in the 3-D domain. These correlations can be used as a quality check for the parameters in every given solution of a contact binary. The empirical laws, extracted out of these correlations, are a useful tool for a quick estimate of physical parameters for the numerous contact binaries found in global sky surveys. The 2-D and 3-D correlation diagramsOur sample is based on the list of 112 contact binaries published by Gazeas & Stepien (2008). These binaries are the only systems with accurate solutions, based on high quality photometric light curves and good radial velocity curves for both components. We show that several relations and correlations exist among the discussed parameters. Some of them may be useful in the future for approximate estimates of masses and radii of contact binaries for which the orbital period is known. In our study we consider component "1" as the presently more massive one. Our assumption is based on the double-lined spectroscopic observations, where the mass ratio is taken as q = M 2 /M 1 ≤ 1.As shown also by Gazeas & Niarchos (2006), the plots of mass and angular momentum versus orbital period gave a direct evidence of evolution into contact, as well as the evolution of A-type W UMa binaries towards the W-type. Figure 1 (upper panel) shows a plot of mass versus orbital period, as well as the equivalent plots of radius and luminosity in logarithmic scale. It was easy to extract empirical laws out of these diagrams, as the correlation of absolute parameters with the orbital period is more than obvious, with an error of approximately 15% (Eqs. 1-6). In the lower panel, the same physical parameters are plotted against orbital period and mass ratio as: M = M(P, q), R = R(P, q), L = L(P, q). The extracted empirical laws give an error less than 5%. ConclusionsThe errors derived from the 3-D correlation equations are significantly small, especially in the prediction of mass and radius. The determination of the physical parameters from the above diagrams is independent of the orbital inclination and (possible) presence of additional objects in a system, derived from the light curve. It is so accurate that it can be used in the opposite way, checking the solutions obtained with the classic procedure. The importance of such an approximation is that we will be able to calculate directly the absolute parameters

show abstract

Masses and angular momenta of contact binary stars

Cited by 62 publications

References 13 publications

Contact Binaries: The Current State

Contact Binaries: The Current State

The Evolution of Low Mass Contact Binaries

Physical parameters of contact binaries through 2-D and 3-D correlation diagrams

Contact Info

Product

Resources

About