Year: 2008
Type: article
Abstract: Well-determined physical parameters of 130 W Ursae Majoris (W UMa) systems were 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 theM–J diagram, which is consistent with the results derived from the analysis of observed spectral type and ofM–R andM–L diagrams of W UMa systems.M–R andM–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. Moreover, the distribution of angular momentum, together with the distribution of the mass ratio, suggests that the mass ratio of the observed W UMa systems decreases with decreasing total mass. This could be the result of the dynamical evolution of W UMa systems, which suffer angular momentum loss and mass loss as a result of the magnetic stellar wind. Consequently, the tidal instability forces these systems towards lowerq values and finally to rapidly rotating single stars.
Authors: Lifang Li, Fenghui Zhang, Zhanwen Han, Dengkai Jiang, Tianyu Jiang
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: bronze
Funder: Chinese Academy of Sciences
Award: G1272654690
OpenAlex ID: W2141216397