Capture radius and synchronization of the white dwarf in the unique magnetic cataclysmic system V1432 Aql |
| |
| Authors: | I L Andronov A V Baklanov |
| |
| Institution: | (1) Astronomy Department, I. I. Mechnikov Odessa National University, Ukraine;(2) Faculty of pre-University education of Youth, Odessa National Maritime University, Ukraine;(3) Crimean Astrophysical Observatory, Ukraine |
| |
| Abstract: | Results from two-color VR photometry of the unique cataclysmic magnetic variable star V1432 Aql and a theoretical model of
these data are presented. The accuracy is improved by using the “mean-weighted comparison star” method. The derivative of
the rotational period is dP/dt = −1.11(±0.016)·10−8. The characteristic synchronization time for the rotational and orbital motions of the white dwarf is 96.7±1.5 years, in
good agreement with theory for the acceleration of an asynchronous propeller owing to the angular momentum of accreting matter.
A third type of minimum detected in the light curve is interpreted in terms of the presence of an arc, or ring, rather than
an accretion disk. A theoretical model is developed for determining the capture radius of accreted matter by the magnetic
field of the white dwarf using the phase difference between the two types of minima associated with the axial rotation. This
parameter is estimated to be 16–28 times the radius of the white dwarf for an inclined column model. A dependence of the main
characteristics of the system on the mass of the white dwarf is derived which yields better values for the range of this quantity
than those determined by indirect methods. For the assumed masses (M1 = 0.9 M⊙ and M2 = 0.3 M⊙) the estimated accretion rate is ∼7×10−10 M⊙. It is shown that in a synchronizing polar the contribution to the change in the period by the variation in the angular momentum
of the white dwarf is negligible compared to the accretion torque. In the future multicolor monitoring is needed for studying
the spin-orbital synchronization and periodic changes in the accretion structure caused by “spinning” of the white dwarf.
__________
Translated from Astrofizika, Vol. 50, No. 1, pp. 135–159 (February 2007). |
| |
| Keywords: | stars white dwarfs-individual V1432 Aql |
| 本文献已被 SpringerLink 等数据库收录！ |
|
