[Aavso-photometry] Variability of GSC 2362-2866

[Dirk Terrell]

On Thu, 26 Jan 2006 16:30:21 +0200, Pertti P„„kk”nen wrote:

>Let me introduce our observation of GSC 2362-2866 in Perseus, which was found 
>to be a variable star during ITM's observation of (93)Minerva. The star 
>appears to be a W UMa eclipsing binary with 7 hours period and variability 
>between V=13.45...14.05. Results of 395 observations and analysis are 

That could potentially be an interesting system. The difference in the
eclipse depths indicates a difference between the surface temperatures
of the two stars, meaning that the thermal coupling is very weak (or
non-existent) and the system might be one of the rare "broken contact"
systems. When the contact is broken, the system becomes semi-detached
with the primary filling the Roche lobe. Because of the expansion of
the primary (due to the fact that it can no longer dump a large
fraction of its luminosity into the secondary), it will transfer matter
to the secondary (which has shrunk away from its Roche lobe because it
is no longer puffed up by that energy from the primary) and there will
be an impact hot spot on the secondary. This will cause the light curve
maximum at phase 0.25 to be higher than at 0.75 (0.0 being the primary
minimum). That is clearly the case in your light curve. Additional U, B
and I photometry would be very useful for this system. Unfortunately
the eclipses appear to be partial and that will limit what a full
analysis of the light curve can tell you, primarily that you cannot get
the mass ratio from the photometry alone so you will need radial
velocities of both stars to figure everything out. 

Dirk

---
Dr. Dirk Terrell
Computer and Mission Systems Section Manager/Astronomer
Southwest Research Institute, Boulder, CO
303-546-9670
http://www.boulder.swri.edu/~terrell/