[vsnet-chat 4742] Re: Eta Carinae

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

Hi Bish and others,

I was interested in the annual variation of eta mentioned by you. Did this
paper by Chris Sterken ever find its way into print? I suppose that to the
eye eta seems like a yellow object (B-V ~0.6) and most of the comparisons in
the 6.0 to 5.4 range are bluer than this. But 0.3 magnitudes seems a large
variation for a colour term. Presumably it's hopeless to try to
sort out the star in the 6.5 to 6.0 range - in the 1950s and 1960s I think -
when the comparison sequence was a mess.

You people have been talking about the S Doradus mechanism but I'm unsure of
the timescale. Is this around the 5 year variation or is it decades or
centuries. Another star of interest - the double peaked Mira R Centauri has
a red and a blue peak. The first peak is relatively normal, with the star
becoming less red just prior to maximum. But there is then a brighter peak
(or was until the last decade) where the star shows, if anything, a slight
reddening. I've always been intrigued by these colours and the overall
physical mechanism which can produce them.

I hope to get set up to do some BVRI measures of some of these stars this
summer. I got a bit lazy last year and didn't do anything for ten months but
I'm feeling astronomical again! Incidentally, Albert lived north of Dunedin,
in Timaru at about 45-46S, but for the last 30 years or so has been in
Nelson
at around 41S. Not too different from Auckland's 37S. Fraser may have become
confused over my latitude of 35S. I work with the Auckland people, who are
not very active on LPVs at the moment, but I'm well north of them - only
50km from the northern tip of NZ in reality.

Regards to all,
Stan

----- Original Message -----
From: Bish Ishibashi <bish@howdy.gsfc.nasa.gov>
To: <vsnet-chat@kusastro.kyoto-u.ac.jp>
Sent: Friday, August 17, 2001 5:31 PM
Subject: [vsnet-chat 4737] Re: Eta Carinae


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