Capture radius and synchronization of the white dwarf in the unique magnetic cataclysmic system V1432 Aql

Authors: Andronov, I.¹; Baklanov, A.²

Source: Astrophysics, Volume 50, Number 1, January 2007 , pp. 105-124(20)

Publisher: Springer

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.

Keywords: stars; white dwarfs-individual; V1432 Aql

Document Type: Research article

DOI: http://dx.doi.org/10.1007/s10511-007-0012-z

Affiliations: 1: Email: il-a@mail.od.ua 2: Email: baklanov@crao.crimea.ua

Publication date: 2007-01-01

Related content

• In this: publication
• By this: publisher
• In this Subject: Astronomy
• By this author: Andronov, I. ;  Baklanov, A.

Website © Publishing Technology. Article copyright remains with the publisher, society or author(s) as specified within the article.

• Terms and conditions
• Privacy policy
• Information for advertisers