ARCSAT ID NUMBER: AS07

DESCRIPTIVE TITLE:  Continuing to monitor the orbital period variations and the transient events in Cataclysmic Variables

PI: Zhibin Dai

OBSERVER(S): Zhibin Dai

UNCERTIFIED/UNTRAINED OBSERVERS:

COLLABORATORS: Paula Szkody
 
CONTACT INFORMATION:
Zhibin Dai
E-mail: daizb@u.washington.edu
off: (206) 610-2788
Res:
Cell: (206) 470-9669

TIME REQUESTED:
My 3.5m schedule is: October 25 and December 14, 2014. And I would return back China in the late half of January 2015. So, I prefer to request the observing time before January 2015. So, I requested the dark time in the following two weeks.   

Priority order        time       moon phase  
       1.        November 17-23    dark
       2.        December 15-21    dark

INSTRUMENT: FlareCam

FILTERS: SDSS ugriz

COMMENTS:

BRIEF SCIENCE JUSTIFICATION:
Besides the dwarf novae with short orbital period CVs, Nova-like variables including SW Sex-type CVs with high accretion rates and Intermediate polars with long orbital periods are also critical to unravel CV formation and evolution. The parameters of CVs located on the high edge of the period gap are especially important for tests of the current standard evolution theory of CVs. Although some of them have been studied before, many newfound CVs with orbital periods between 3~4 hr lack investigations. This means that updated analyses for them are necessary. We expect to do high time resolution photometry for the bright targets. After literature searches, we found that there are over 200 CVs with magnitudes less than 18 on the upper edge of the period gap. Among these, the eclipsing systems comprise nearly 30 percent. By modeling the complete light curves, their basic physical and geometric parameters could be constrained. Additionally, we also expect to detect many more transient events in Nova-like stars since the permanent outburst state may result in more valuable phenomena.

In the summer quarter, we have already obtained some good results including the SU Uma type dwarf novae HT Cas, WZ Sge; the U Gem type dwarf nova EX Dra and the SW Sex type nova-like PX And. In particular, the reduced light curve of the U Gem type dwarf nova EX Dra presents a good eclipse profile and small quasi-oscillations outside eclipse. According to our experience in this observing quarter, we hope to reach the fainter objects and achieve better results by adjusting some observation parameters in the next quarter.