Issue |
A&A
Volume 407, Number 3, September I 2003
|
|
---|---|---|
Page(s) | 987 - 998 | |
Section | Stellar structure and evolution | |
DOI | https://doi.org/10.1051/0004-6361:20030851 | |
Published online | 17 November 2003 |
The near-synchronous polar V1432 Aql (RX J1940.1–1025): Accretion geometry and synchronization time scale
1
Institut für Astronomie und Astrophysik, Universität Tübingen, Sand 1, 72076 Tübingen, Germany
2
Institut für Theoretische Physik und Astrophysik, Universität Kiel, Leibnizstr. 15, 24098 Kiel, Germany
3
Max-Planck-Institut für extraterrestrische Physik, Giessenbachstr. 1, 85748 Garching, Germany
4
Integral Science Data Centre, 16 Chemin d'Ecogia, 1290 Versoix, Switzerland
5
Sternwarte Sonneberg, Sternwartestr. 32, 96515 Sonneberg, Germany
6
Center for Astrophysics and Space Science (CASS), Univ. California, San Diego, California, USA
Corresponding author: R. Staubert, staubert@astro.uni-tuebingen.de
Received:
19
March
2003
Accepted:
28
May
2003
The magnetic Cataclysmic Variable (mCV) V1432 Aql
(RX J1940.1–1025) belongs to the four-member subclass of
near-synchronous polars with a slight non-synchronism (<2%)
between the spin period of the white dwarf and the binary period. In
these systems the accretion geometry changes periodically with phase
of the beat cycle. We present the application of a dipole accretion
model for near-synchronous systems developed by Geckeler & Staubert
(1997a) to extended optical and X-ray data.
We detect a significant secular
change of the white dwarf spin period in V1432 Aql of
s/s
from the optical data set alone. This corresponds to a
synchronization time scale
yr,
comparable to the time scale of 170 yr for V1500 Cyg.
The synchronization time scale in V1432 Aql is in excellent
agreement with the theoretical prediction from the dominating
magnetic torque in near-synchronous systems. We also present period
analyses of optical CCD photometry and RXTE X-ray data, which argue
against the existence of a 4000 s period and an interpretation of
V1432 Aql as an intermediate polar. The dipole accretion
model also allows us to constrain the relevant parameters of the
accretion geometry in this system: the optical data allow an
estimate of
the dimensionless parameter
, with a lower limit for
the threading radius of
(68% confidence).
Key words: stars: variables: general / stars: binaries: eclipsing / stars: individual: V1432 Aql; RX J1940.1–1025 / stars: magnetic fields / X-rays: stars
© ESO, 2003
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.