 |
 |
|---|---|
|
V1006 Cyg: a new SU UMa CV
On Aug. 14.1 2007, E. Muyllaert (Belgium) spotted this star at mag. 13.6, that is clearly in a very bright outburst. A similar bright state was observed on June 2006. I was imaging NGC 891 when I received the alert announcing this event, so the 28cm-f/8.3 SC + Paramount ME and SBIG ST8-XME (part of the Virtual Telescope Project) was remotely slewed to this very-high-priority target, which appeared still bright. Time-resolved photometry was promptly started and real-time data reduction performed: after about 30 minutes, it was clear that V1006 Cyg was clearly showing some modulation, suggesting superhump-like features (possibly early superhumps). This sistem has an orbital period of 142.6 minutes, so the is relatively 'slow', requiring a long coverage to spot a full cycle. Also, with that period, V1006 Cyg sits in the middle of the so-called 'period gap'. So, these observations for the first time suggested the SU UMa nature of this cataclysmic variable star. I was able to track this star until the sky brightened (for a total of 1.6h), getting the data below.
The following night, the Virtual Telescope observed the star again, this time all-night-long, finding it a bit fainter. The source was still humping (with an amplitude of 0.05 mag) and the lightcurve showed a decline. The plot below is the resulting lightcurve (red dots are binned points over 3 minutes).
Joining both datasets, the longer baseline provided a chance to estimate the modulation's period: the best estimate by PDM technique, after detrending the plot, is 2.3077h, shorther than the orbital period. Of course, I assumed the period did not change. The phased data follows (blue dots are the first night):
On Aug. 16 I managed to follow the star for another night, getting the dta below.
Superhump-like features seem to be emerging and the period analysis (performed over the last two nights of data) suggests a candidate of Psh=2.3839h, significantly longer than the orbital one (typical for superhumps). The data available so far provide the following photometric evolution.
The variable was observed for several nights, obtaining the full lightcurve below (click on it to get the full image). Of course, the differential scale is referred to the same reference star. The star faded to quiescence, after such mid-outburst, where it showed evident hump-like modulation 'drove' basically by its orbital period (altough sometimes longer periods could be possibly detected).
I wish to thank Danilo Pivato for taking the wide-field above. The Virtual Telescope - 21 August 2007 |
