[vsnet-chat 2099] Re: [vsnet-alert 3203] VW Hyi in outburst ... again

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

Lew & Berto,

VW Hydri was one of the early stars we looked at from Auckland in the late
1960s when we began pep. The normal outbursts are essentially random
although periodicities can be derived in the manner mentioned by Lew. There
were suggestions that the interval became longer as it approached the next
superoutburst. V803 Cen seems to do this but the timescale is much shorter.

The superoutbursts of VW Hydri and other SU UMa stars showed a dual nature
in that for a while the intervals averaged 169 days then would switch to a
longer period - say 186 days or thereabouts. Vogt analysed a lot of these
stars in the 1970s as did Marino and I in Auckland, then I noticed Mattei
repeated the analysis for some northern stars in an AAVSO publication. The
SO are almost predicatable but do depend on the less predictable ordinary
outbursts.

VW Hydri usually only has normal outbursts close together immediately
preceding a superoutburst when they can be as little as 7 days apart. This
seems to occur when a 'precursor' doesn't quite fire up a superoutburst.
But as Berto says the behaviour may have changed - do you have recent
records, Berto? When was the last superoutburst. WX Hydri seems to be
another star where the outbursts change frequency - Danie Overbeeck was
commenting about this recently.

I've been looking at V803 Cen again recently - its behaviour seems to hve
changed since 1997 but I've really got too little data to be certain of
much. It would be great if it was a couple of magnitudes brighter! Or a bit
farther north.

Regards,
Stan
----------
> From: Lew Cook <lcoo@yahoo.com>
> To: Berto Monard <LAGMonar@csir.co.za>; observations@aavso.org;
vsnet-chat@kusastro.kyoto-u.ac.jp
> Subject: [vsnet-chat 2098] Re: [vsnet-alert 3203] VW Hyi in outburst ...
again
> Date: Saturday, July 10, 1999 10:53 AM
> 
> --- Berto Monard <LAGMonar@csir.co.za> wrote:

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