[vsnet-chat 132] Re: WX Hyi history (W S G Walker)

[Taichi Kato <tkato@kusastro.kyoto-u.ac.jp>]

Stan Walker has provided the following information:

From astroman@voyager.co.nz Sat Feb 22 09:19 JST 1997
Date: Sat, 22 Feb 1997 13:13:06 -0800
From: W S G Walker <astroman@voyager.co.nz>
Subject: Re: [vsnet-chat 128] WX Hyi history

Taichi Kato wrote:
> 
>     After reading recent postings on the possible change in outburst
> behavior of WX Hyi, I have noticed in the GCVS 3rd the star was classified
> as a Mira star (10.7-14.2p).  Some references show the "peculiar" blue color
> and rapid variation of this star were noted by Philip in IAUC 2348 and
> confirmed by subsequent authors including Sonneberg researchers (IBVS 578).
> 
>     Is this a famous story?

Not especially. At that stage - about the early to mid 1970s - there was 
the thought that some SU UMa stars might have been catalogued as Miras 
due to the periods of the superoutbursts - say 180 to 300+ days. I think 
that WX Hydri was found independently of this search but if Albert Jones 
reads this he could probably background it as there was quite a bit of 
interest in this star amongst the VSS here and he seemed to have made 
quite a few measures before we looked at the star in Auckland. 

The other thing to remember is that UBV photometry was relatively "new" 
at that time and the idea of finding stars by their ultraviolet 
signatures (called "excesses" then) was not well established, 
particularly amongst the amateurs looking at these stars. From memory at 
minimum this star has B-V about -0.1 and U-B about -1 so it stands out 
from its neighbours. There were some interesting arguments about 
identities of stars when the pe people would insist that the some star 
was catalogued incorrectly because of the colours. 

SY For was also studied about this time as it had been catalogued as a 
CV, then recatalogued as an SR star. It's quite reddish - and has a 
period rather different from the GCVS value - but also has a very strong 
UV signature. Lloyd-Evans at SAAO referred to this as a flat star, on 
account of its large disc. The pe measures show interaction and I don't 
really know how it should be classed. Z Apodis is another star in the 
GCVS as a CV but is in reality a cepheid of some sort. Its colours are 
quite ordinary but the period showed a slow change. 

We gave CVs away in Auckland in about 1984 as the challenging ones seemed 
to have become too faint. But the interest has been rekindled after 
reading Brian Warner's book on these stars - and finding out how 
effective CCD photometry is in this area. 

Regards,
Stan Walker

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