[vsnet-alert 11321] Optical Photometry of TT Ari Simultaneous with the Suzaku Satellite Observations: QPOs in the Negative Superhump State: ATel #2122

[Ivan Andronov]

http://www.astronomerstelegram.org/?read=2122

Optical Photometry of TT Ari Simultaneous with the Suzaku Satellite Observations: QPOs in the Negative Superhump State

ATel #2122; Ivan L. Andronov (Odessa National Maritime University, Ukraine), Alexei V. Baklanov (Crimean Astrophysical Observatory, Ukraine), Alexios Liakos, Panagiotis Niarchos (Department of Astrophysics, Astronomy and Mechanics, National and Kapodistrian University of Athens, Greece)
on 9 Jul 2009; 17:44 UT


Subjects: Optical, X-ray, Binaries, Cataclysmic Variables, Variables

In the "vsnet-alert 11316", Akira Imada called for simultaneous X-ray/optical observations of TT Ari for July 6,7. 

We observed the star using two 40-cm telescopes in Ukraine (V filter) and Greece (no filter, i.e. "wide R"). 

As a main comparison star, "c" was used with V=10.99 (Goetz 1985, IBVS 2823) and R=10.41 (Efimov et al., 1998, BCrAO, 94, 115). The mean brightness is R~11.21, which is consistent with the bottom brightness level observed for the "negative superhump" state (Kim et al., 2009&A, 496, 765). The light curves ( http://andronov.astronomy.org.ua/TT_Ari-RP-Gr.jpg ) show QPOs. The V curve has much larger scatter because of smaller exposure and the presence of the V filter, and also a larger amplitude of the QPOs. 

The "Running parabola" "Lambda"-scalegram (Andronov, 2003, ASPC, 292, 391) shows few peaks: P=0.0046d=6.6 min, semi-amplitude r=21 mmag; P=0.0102d=14.3min, r=17 mmag; P=0.0303d=44min, r=13mmag which are consistent with 3 peaks at the periodogram ( http://andronov.astronomy.org.ua/TT_Ari-2periodogram.gif ). 

The presence of the QPOs is typical for the "negative superhump" state, as QPOs nearly disappear in the "Positive superhump" state.