On The Coronal Activity of the RS CVn-Type Binaries

Authors : Osman DEMİRCAN and Hasan AK

Pages : 433-444

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Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :We re-analysed the behaviour of coronal activity of the RS CVn-type binaries as a function of stellar and orbital parameters. Highly significant correlations were found between the x-ray luminosity Lx and the stellar radius R, the Roche lobe filling fraction G, and the Alfven radius RA. The correlations of Lx with the mass M, the absolute magnitude MV, the surface gravity g, the Roche lobe filling fraction G, and the Alfven radius RA are likely to be due to correlations of these quantities with the stellar radius R. Surprisingly, no correlation of Lx on the color insert ignore into journalissuearticles values(B-V);, the rotation velocity Vrot, and the Rossby number RO is observed. However, significant correlations were found between the mean surface x-ray flux Fx=Lx/Rc2+Rh2 with the orbital period Porb, the rotation velocity Vrot, the Rossby number RO. The activity-radius insert ignore into journalissuearticles values(and radius dependent parameters: G, M, g, MV, and RA); correlations are mostly disappear when the mean surface flux Fx is used as the activity measure. We think the radius R insert ignore into journalissuearticles values(infact the surface area 4 p R2); in Lx-R correlation represents the filling area S of the active regions on the stellar surface. The Lx thus increases with increasing surface area 4 p R2 insert ignore into journalissuearticles values(in fact with increasing S);. Slightly decreasing trend of the surface flux with the evolution off the main sequence insert ignore into journalissuearticles values(age or R2); can be understood in terms of the decreasing filling fraction insert ignore into journalissuearticles values(S/4 p R2); of the active regions with age.
Keywords : Turk J Phys, 23, 1999, , 433 444 Turk J Phys, vol 23, iss 2