[vsnet-chat 7481] TT Ari: Will Luminosity Changes Cause Positive/Negative Superhump Switches ?

[Ivan Andronov]

In
[vsnet-alert 11460] TT Ari fading,

Taichi Kato informs on a possible fading of TT Ari. According to Kraicheva et
al. 1999A&A...351..607K and Stanishev et
al. 2001A&A...379..185S, the positive/negative superhump state is dependent on
luminosity.

Kim, Y.; Andronov, I. L.; et al.
http://cdsads.u-strasbg.fr/abs/2009A&A...496..765K found that this behavior is
dependent not only on luminosity, but also on the "history" of changes, i.e. at
the same luminosity level, the QPO
characteristics split into two groups - with small and large amplitude of the
QPOs.

So, if now TT Ari is in a state of luminosity changes, it will be interesting to
make all-night observations in R or VRVR to
study variability of the characteristics of the 15-25 minutes QPOs and of the
0.13d (negative)- 0.143d (positive)
superhumps. Typically, QPOs are more pronounced in the negative suprhump state,
while at the positive superhump
state, the superhumps show an asymmetric wave
(cf. Andronov et al. 2005IBVS.5664....1A)

Ivan L.Andronov
Department "High and Applied Mathematics"
Odessa National Maritime University