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| Paper: |
Asynchronous Polar BY Cam: the Spin-orbital Synchronization and Variation
of Accretion Geometry on the 8-year Time Scale |
| Volume: |
469, 18th European White Dwarf Workshop (EUROWD12) |
| Page: |
343 |
| Authors: |
Pavlenko, E.; Andreev, M.; Babina, Y.; Malanushenko, V. |
| Abstract: |
Attempts to estimate the time of a spin-orbital
synchronization for asynchronous polar BY Cam have been made many
times since 1994 year. However the estimates obtained did not
coincide in a wide region, varying from 150 years (Piirola et al. 1994) up to >3500 years (Kafka et al. 2005). We have
undertaken photometric observations of BY Cam over 8.1 years
(2004 – 2012) and collected an array of data covering 998 hours
during 178 nights. Analyzing the data, we have obtained the most
reliable estimate of the spin-orbital time synchronization, Ts
= 250±20 years, which agrees very well with both Ts = 150–
290 yrs for asynchronous polar V1500 Cyg (Pavlenko & Pelt 1991);
(Stockman et al. 1988) and the theoretically predicted Ts < 1000 yr
for asynchronous polars as a whole (Andronov 1987). We also found
that the accretion stream switches between two dipole magnetic
poles and the equatorial magnetic poles during a synodic ∼
15-d cycle; the number of switching and their phases can be kept
during neighbor cycles but varies on a scale of years. Probably
this may depend on the phase of the long-term ∼ 1500 day
periodicity (Andreev et al. 2012). |
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