A NEW DEEP LOW STATE OF TT ARI?

Abstract

In this report, results of spectral and photometric study of TT Ari, one of the brightest cataclysmic variable stars, are reported. Observations were conducted in October and December, 2008 and November, 2009. Spectral observations on 12 and 13 November, 2009 detected the star in its second “deep low state” (DLS, hereinafter). Actually, the first hints to the brightness decrease appeared in late September, 2009 and became clear on October 3. In general, our spectra out of DLS are concordant with earlier data, althought some distinctions at this stage are registered too. In particular, both the brightness and equivalent widths (EWs hereinafter) of the emission lines show variations that probably have periodic character. Observed variations in the symmetry of the wide absorption lines of Balmer series (beginning from Hβ) might be caused by the appearance of the anti P Cyg profile, and Hα exhibits P Cyg profile consisting of two components. The spectra of TT Ari obtained at DLS remind those of T Tau stars of late G or early K spectral classes. Mean EWs of some emission lines at different epochs are given. An unusually strong increase of EWs is detected at low energetic state of TT Ari which exceeds those obtained at high energetic state by up to 20–25 times. The mean EWHα/EWHβ ratio at “high” and “low” states shows that formation of these lines can be explained, at least partly, within a simple photoionization‐recombination model.