[vsnet-alert 12275] TT Ari: Brighter with Positive Superhumps and QPOs

[Natalia Virnina]

TT Ari: Brighter with Positive Superhumps and QPOs

According to our most recent CCD observations (V-Bessel), TT Ari becomes
brighter.
The periodogram analysis was made using one-harmonic approximation
(Andronov, 1994OAP.....7...49A) realized in the program MCV (Andronov I.L.,
Baklanov A.V., 2004, Astronomy School Reports, 5, 264,
http://uavso.pochta.ru/mcv). It shows three peaks at 0.1432d (which is
apparently close to the "positive superhump" period, cf. Skillman et al. ,
1998, ApJ, 503 L67; Andronov et al., 1999, AJ, 117, 574), and also at
0.0478d=69 min. The third (according to the height) peak at the periodogram
occurs at 0.0105d=15 min (which is characteristic for quasi-periodic
oscillations previously seen in TT Ari, cf. Kim et al. 2009A&A...496..765K.
Using a 3-period harmonic fit for the data using these values of "periods",
we get semi-amplitudes of 0.077+-0.015, 0.077+-0.018 and 0.046+-0.015,
respectively. The mean brightness is V=13.101+-0.012.
Although the semi-amplitude of the QPOs only slightly exceeds 3 sigma, its
value is remarkably similar to that of 0.045 mag (VR) reported by Andronov
et al. (2004, IBVS 5664).
   The system seems to gradually return from its low luminosity state
observed since September, 2009 and reported in numerous VSNET circulars by
Natalia Virnina and Taichi Kato. Its current state resembles previously
reported "positive superhump" state with lower-amplitude QPOs.


JD                    V mag  observer
2455485.83868 13.2395 VIR
2455485.84149 13.0270 VIR
2455485.84429 13.0990 VIR
2455485.84711 13.1183 VIR
2455485.84992 13.0539 VIR
2455485.85274 13.0559 VIR
2455485.85556 13.2086 VIR
2455485.85837 13.3438 VIR
2455485.86120 13.1264 VIR
2455485.86400 13.0970 VIR
2455485.86683 13.2934 VIR
2455485.86964 13.2510 VIR
2455485.87247 13.1463 VIR
2455485.88034 13.1726 VIR
2455485.88303 13.2307 VIR
2455485.88574 13.0692 VIR
2455485.88911 13.0419 VIR
2455485.89295 12.9339 VIR
2455485.89675 12.9773 VIR
2455485.89946 13.0563 VIR
2455485.90420 13.0859 VIR
2455485.90691 13.0849 VIR
2455485.91061 13.1077 VIR
2455485.92127 13.1592 VIR
2455485.92413 13.0918 VIR
2455485.92699 12.9710 VIR
2455485.92984 13.0314 VIR
2455485.93270 12.9650 VIR
2455485.93554 13.0338 VIR
2455485.93839 12.8921 VIR
2455485.94150 12.9976 VIR
2455485.94436 12.9703 VIR
2455485.94721 12.9160 VIR
2455485.95007 13.1115 VIR
2455485.95295 13.0509 VIR

N. A. Virnina, I. L. Andronov
Department of High and Applied Mathematics
Odessa National Maritime University, Ukraine.