[vsnet-alert 10788] Re: ST CHA in outburst?

[Berto Monard]

Hello Boris and al,

Just for interest's sake. I observed ST Cha for about 4 hours on 12 Dec 2006. There was no sign of modulation around the then 14.1 (unfiltered CCD) magnitude. The only star that varied was the check star I chose...

Regards,

Berto Monard
Bronberg Observatory / CBA Pretoria

>>> <Boris.Gaensicke at warwick.ac.uk> 02/12/2008 15:38 >>>
Hi John, Martin, et al., 

> Summary : ST Cha - not particular in outburst, not necessarily a CV, 
> 14.6h is might actually be a fairly typical min mag (though Rod Stubbins 
> data show it can be fainter).

The spectrum in Steiner's paper, 

http://adsabs.harvard.edu/abs/1988ASPC....1...67S 

looks like an optically thick (=high mass transfer) accretion disc, i.e. 
either a dwarf nova in outburst, or a novalike variable, in fact, Steiner 
et al. thought it could be an UX UMa novalike, or possibly an LMXB. The 
latter would be exciting, but is probably less likely. The other 
interesting point they make is that the system is eclipsing with a period 
around 7h... that should easily be tested by a few nights of time series. 

There are a number of such CVs around, weak amplitude variability, and 
spectra with shallow but broad Balmer absorption, and maybe just a bit of 
Halpha emission - good (frequent) long-term monitoring will help to tell 
if they are nova-like variables (=always "on"), or possibly Z Cam DN with 
long stand-stills. 

With a typical brightness of ~14.5, it looks like a burst of time-series, 
plus a denser long-term monitoring should clarify the nature of the 
system. 

Cheers, 

Boris


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Dr. Boris Gaensicke                  www.warwick.ac.uk/go/BorisGaensicke 
Associate Professor                        Boris.Gaensicke at warwick.ac.uk 
Department of Physics
University of Warwick
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