[vsnet-chat 7255] Unique Magnetic Cataclysmic Variable V1432 Aql

[Ivan L.Andronov]

Unique Magnetic Cataclysmic Variable V1432 Aql.
Third Type of Minima, Capture Radius and Synchronization
I.L. Andronov^{1,2}
A.V. Baklanov^{1,2} 
V. Burwitz^{3,4}
$^1$Department of Astronomy, Odessa National University,
  T.G.Shevchenko Park, UA-65014, Odessa, Ukraine,\email{il-a at mail.ru}
$^2$Crimean Astrophysical Observatory, UA-98409 Nauchny, Ukraine
$^3$Max-Planck-Institut f\"{u}r extraterrestrische Physik, D-85741 Garching,
Germany
$^4$Observatori Astron\`{o}mic de Mallorca, E-07144 Costitx, Spain

\abstract{Results of a CCD study of the variability of the unique magnetic
cataclysmic variable V1432 Aql in the Astronomical Observatory of Mallorca
are presented. The "multi-comparison star" method had been applied for
better accuracy estimates. The linear ephemeris based on 76 timings of
orbital dips for 1993--2004  is $HJD_{min} = 2451492.11112(14) +
0.140235812(12)\cdot(E-16347).$ For the wide minima owed to the spin
variability, the quadratic ephemeris
$HJD_{spin}=2449638.327427(74)+0.14062831(23)\cdot E -7.81(11)\cdot
10^{-10}E^{2}$ was determined. The rate of the spin-up of the white dwarf
corresponds to the synchronization time-scale is determined to be
$(96.7\pm1.5)$ years, in an agreement with theoretical model of the
accretion torque.
The third type of minima were detected, which occur with the spin period. It
was interpreted by presence of the second accretion column, and an "arc"
accretion, or an accretion ring instead of disk. Using the phase shift
between two types of the spin minima, the equatorial radius of the magnetic
field line at continuation of the accretion column was estimated to be 16-28
times larger than the radius of the white dwarf for the model of "inclined
columns". For adopted values of masses $M_1=0.9$ and  $M_2=0.3$ solar
masses, the estimated accretion rate is $\sim7\cdot10^{-10}M_\odot/{\rm yr}.$
A further multi-colour monitoring is needed for studies of late stages of
the "spin-orbital" synchronization and periodic changes of the accretion
geometry caused by "idling" of the white dwarf.