[vsnet-chat 70] Re: EG Cnc - first one?

[W S G Walker <astroman@voyager.co.nz>]

Fraser Farrell wrote:

> I would have liked to observe this one for myself, but looking through
> the top of Adelaide's skyglow at 13th mag stars is a bit difficult for
> me. However, there seems to be a similar star in the other direction
> where my sky is dark - WX Hydri.
> 
> The VSS RASNZ Circulars for October & November arrived this week.
> Here's some more information about that odd superoutburst of WX Hyi:
> 
> JD of maximum
>   2450000+      duration (rise-peak-fall) days     magnitude
> -----------     ------------------------------     ---------
>  363                2.9 - 5.0 - 5.7   (supermax)     12.0
>  380                1.1 -     - 0.9                  12.5
>  386                1.4 - 0.7 - 1.0                  12.5
>  394                1.2 - 0.2 - 2.3                  12.4
>  406                2.0 -     - 1.                   12.8
>  416  (Nov 28)      1.8 - 1.  - 1.1                  12.0

> How many of those maxima represent re-brightenings of a superoutburst?
> Maybe all of them?  WX Hyi certainly didn't "slow down" after the
> superoutburst like many other UGSS's would have!  In fact it may be even
> more active than indicated; there has been a lot of cloudy weather in
> the Southern Hemisphere lately.
> 
> WX Hyi's frequency of outburst was about 2 or 3 times per month a few
> years ago, and outbursts were typically less than 2 days long.  Even its
> superoutbursts lasted no more than a week.  Now it is going off more
> frequently, and for longer maxima. Taichi Kato seems to be right in
> suggesting WX Hyi is trying to join "The ER UMa Club".

Greetings, Fraser,

I saw your note about WX Hydri. Rather than it being more active lately 
it seems to have reverted to the earlier behaviour patterns. We looked at 
this star from Auckland years ago - I think about the mid-1970s - looking 
for an orbital period using pep. At that time it seemed to be bright 
almost more often than it was faint and weekly outbursts weren't unusual. 

Not too long ago (in the last couple of years) it was suggested that WX 
Hydri had stopped having outbursts. I'm unsure whether this was normal or 
super, or even when the supposed cessation occurred. Was this ever true?

In the normal outbursts we measured there was no pause at maximum - 
decline began immediately as with several other southern UGSU stars - 
although this may be difficult to pick visually. The supermaxima had good 
superhumps at the start but they soon became rather messy.

I meant to look at this star during the early summer but didn't manage 
it. Now it's just a little low - but maybe next year? I would have tried 
EG Cancri but 1997 seems to be a year for tropical storms hitting 
northern NZ!

Stan Walker

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