[vsnet-chat 269] New Variables & Nomenclature

[Stan Walker <astroman@voyager.co.nz>]

Dear Chatters,

One might almost think that the VS cataloguing sysytem is nearing some sort
of breaking point. The present idea of using constellation boundaries is
reasonable but you strike problems when you haven't got an atlas handy and
wish to check whether something is a known variable. But spare some thoughts
to the total number of variables out there.

At PEP4 in 1993 Brian Warner touched briefly on a survey using a fixed CCD
camera which had found 60,000 new variables in a strip of sky two degrees wide. 

Programmes like John Percy's SARV  observations seem to be proving that
almost all M giant stars are variable - with the possible exception of M0
stars. 

In 30 years' of photoelectric measures at Auckland Observatory we have found
dozens of K and M stars which seem to vary by 2-5% over a timescale of
years. We thought this might be spotty stars - they've all got convective
envelopes - and the rotation times are probably measured in months or years.
But a graduate student at Mt John found micropulsations with radial
velocities of about 50 km/s. None of these are in the catalogues - who'd be
interested? Other people find these as well and they're still variables. The
suggestion is that a substantial percentage of all K and M stars are
moderately variable on a time scale of a decade. There must be thousands of
these objects known.

Someone, somewhere, is shortly going to set up a CCD survey programme which
will document hundreds or thousands of low amplitude, slow variables. At
present Percy seems to call these stars SRs but the class really is designed
for larger amplitude objects.

The GCVS is presently five volumes which take up a lot of room. When I use
Excel I have to break it into two pieces initially so that programme - which
is not too bad a spreadsheet - can cope. And these are only the stars in our
own galaxy, with a few misfits like S Doradus and friends.

Will we shortly end up with the main catalogue, a catalogue of known but
presumably uninteresting variable stars, and the catalogue of suspected
variables?

Regards,
Stan Walker

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