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Curious Variables Experiment (CURVE). RZ LMi - the Most Active SU UMa Star

Olech A., Wiśniewski M., Złoczewski K., Cook L. M., Mularczyk K., Kędzierski P.

Acta Astronomica

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2008

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Vol. 58, No. 2

131--152

EN

We report extensive photometry of the frequently outbursting dwarf nova RZ Leo Minoris. During two seasons of observations we detected 12 superoutbursts and 7 normal outbursts. The V magnitude of the star varied in range from 16.5 mag to 13.9 mag. The superoutbursts occur quite regularly flashing every 19.07(4) days and lasting slightly over 10 days. The average interval between two successive normal outbursts is 4.027(3) days. The mean superhump period observed during the superoutbursts is Psh=0.059396(4) days (85.530±0.006 min). The period of the superhumps was constant except for one superoutburst when it increased with a rate of P/Psh=7.6(1.9)×10-5. Our observations indicate that RZ LMi enters the stage of permanent superhumps, both in superoutbursts and quiescence. This may indicate that decoupling of thermal and tidal instabilities play important role in ER UMa systems. No periodic light variations which can be connected with orbital period of the binary were seen, thus the mass ratio and evolutionary status of RZ LMi are still unknown.

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Curious Variables Experiment (CURVE). CCD Photometry of Dwarf Nova V660 Herculis

Olech A., Złoczewski K., Cook L. M., Mularczyk K., Kędzierski P., Wiśniewski M.

Acta Astronomica

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2005

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Vol. 55, No. 2

237--246

EN

We report extensive photometry of the dwarf nova V660 Her. During our campaign, lasting from August 2003 to November 2004, we recorded one bright eruption which turned out to be a superoutburst lasting about 15 days and having amplitude of ≈4.5 mag. Clear superhumps with a mean period of Psh=0.080924(18) days (116.53±0.03 min) were present during all nights of the superoutburst. The period of the superhumps was not stable and in the interval covered by our observations it decreased with a rate of P/Psh=-4.0(1.4)×10-5. Based on our data and the known orbital period of the binary we calculate the period excess of 3.4±0.1%, which is typical for an SU UMa star at this orbital period. This value indicates that the mass ratio of the system is q=0.154

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Curious Variables Experiment (CURVE). TT Bootis - Superhump Period Change Pattern Confirmed

Olech A., Cook L. M., Złoczewski K., Mularczyk K., Kędzierski P., Udalski A., Wiśniewski M.

Acta Astronomica

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2004

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Vol. 54, No. 3

233--247

EN

We report extensive multi-station photometry of TT Boo during its June 2004 superoutburst. The amplitude of the superoutburst was about 5.5 mag and its length about 22 days. The star showed a small re-brightening starting around the 9th day of the superoutburst. During entire bright state we observed clear superhumps with amplitudes from 0.07 mag to 0.26 mag and a mean period of Psh=0.0779589(47) days (112.261±0.007 min). The period was not constant but decreased at the beginning and the end of superoutburst and increased in the middle phase. We argue that the complicated shape of the O-C diagram is caused by real period changes rather than by phase shifts. Combining the data from two superoutbursts, 1989 and 2004, allowed us to trace the birth of the late superhumps and we conclude that it is a rather quick process lasting about one day.