Issue |
A&A
Volume 394, Number 1, October IV 2002
|
|
---|---|---|
Page(s) | 231 - 239 | |
Section | Interstellar and circumstellar matter | |
DOI | https://doi.org/10.1051/0004-6361:20021136 | |
Published online | 04 October 2002 |
VY Sculptoris stars as magnetic cataclysmic variables
1
UMR 7550 du CNRS, Observatoire de Strasbourg, 11 rue de l'Université, 67000 Strasbourg, France e-mail: hameury@astro.u-strasbg.fr
2
UMR 7095 du CNRS, Institut d'Astrophysique de Paris, 98bis boulevard Arago, 75014 Paris, France e-mail: lasota@iap.fr
Corresponding author: J.-M. Hameury, hameury@astro.u-strasbg.fr
Received:
14
May
2002
Accepted:
30
July
2002
We show that the absence of outbursts during low states
of VY Scl stars is easily explained if white dwarfs in these
systems are weakly magnetized ( G
cm3). However, some of the VY Scl stars are observed to have
very slow declines to minimum and similarly slow rises to maximum.
The absence of outbursts during such intermediate (as
opposed to low) states, which last much longer than typical
disc viscous times, can be explained only if accretion discs are
absent when their temperatures would correspond to an unstable
state. This requires magnetic fields stronger than those
explaining outburst absence during low states, since white dwarfs
in this sub-class of VY Scl stars should have magnetic moments
G cm3 i.e. similar to those of
Intermediate Polars. Since at maximum brightness several VY Scl
stars are SW Sex stars, this conclusion is in agreement with
recent claims about the magnetic nature of these systems.
Key words: accretion, accretion discs / instabilities / stars: novae, cataclysmic variables / stars: binaries: close
© ESO, 2002
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