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On the Eclipsing Cataclysmic Variable Star HBHA 4705-03

Rutkowski A., Ak T., Marsh T. R., Eker Z.

Acta Astronomica

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2013

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Vol. 63, No. 2

225--238

EN

We present observations and analysis of a new eclipsing binary HBHA 4705-03. Using decomposition of the light curve into accretion disk and hot spot components, we estimated photometrically the mass ratio of the studied system to be q=0.62±0.07. Modeling of the system yields the following fundamental parameters: white dwarf mass M1=(0.8±0.2) Msun, secondary mass M2=(0.497±0.05) Msun, orbital radius a=1.418 Rsun, orbital inclination i=(81.°58±0.°5), accretion disk radius rd/a=0.366±0.002, and accretion rate M=(2.5±2)x1018 [g/s] (3×10-8 Msun/yr). Power spectrum analysis revealed a set of possible low-period Quasi Periodic Oscillations centered at the frequencies f1=0.00076 Hz, f2=0.00048 Hz and f3=0.00036 Hz. The system B-V=0.04 mag corresponds to a dwarf nova color during an outburst. The light curves of HBHA 4705-03 suggest that it is a nova-like variable star.

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Dwarf Nova V1040 Centauri and Variable Stars in its Vicinity

Rutkowski A., Pietrukowicz P., Olech A., Ak T., Złoczewski K., Poleski R., Tappert C., Eker Z.

Acta Astronomica

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2011

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Vol. 61, No. 4

345--357

EN

We present the results of a photometric campaign of the dwarf nova V1040 Cen. The light curve shows two normal outbursts with recurrence time ≈40 days and amplitude ≈2.5 mag. Quiescence data show oscillations with periods in the range ≈0.1 days (2.4 h) to ≈0.5 days (12 h) of unknown origin. We measured the orbital period of V1040 Cen to be Porb=0.060458(80) days (1.451±0.002 h). Based on the MV-Porb relation we found the distance of V1040 Cen to be 137±31 pc. In this paper we also report the detection of eleven new variable stars in the field of the monitored dwarf nova.

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2009 Superoutburst of Dwarf Nova 1RXS J053234.9+624755

Rutkowski A., Olech A., Poleski R., Sobolewska M., Kankiewicz P., Ak T., Boyd D.

Acta Astronomica

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2010

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Vol. 60, No. 4

337--355

EN

We present photometric observations of the dwarf nova 1RXS J053234.9+624755. We performed a detailed analysis of the superoutburst that occurred in August 2009. We found the superhump period to be Psh=0.057122(14) days. Based on the O-C diagram we conclude that Psh increased during the plateau at the rate of dPsh/dt=(9.24±1.4)×10-5. Both the O-C analysis and evolution of the superhumps light curve favor the model in which superhumps originate in a variable source located in the vicinity of the hot spot. In addition, the evolution of the light curve suggests that the superhump light source approaches the disk plane as the superoutburst declines. Detailed analysis of the superoutburst plateau phase enabled us to detect a signal which we interpret as apsidal motion of the accretion disk. We detected additional modulations during the final stage of the superoutburst characterized by periods of 104 s and 188 s which we tentatively interpret as quasi periodic oscillations. Estimations of A0 and An are in agreement with the dependence between the amplitude of superhumps and the orbital inclination.