[vsnet-chat 89] Re: SRc variables as supernova progenitors

[Toshihito Ishida <ishida@nhao.go.jp>]

Dear T. Kato-san and chatters; 

Taichi Kato wrote in the message received on Sun Feb 16 00:01:09 1997
> 
> > >     It's a surprise to know SRc variables in the Galaxy are so rare.
> > > May I have some more questions regarding this?
> > 
> > I actually didn't know it's rare or not when I wrote this sentences.  
> > But, after receiving Kato-san's mail, I tried to make a quick 
> > inspection on this point from the electronic GCVS4 data in Selected 
> > Astronomical Catalogs, volume 1 (CD-ROM distributed by ADC, NASA).  
> 
> (omitted)
> 
> > Inspecting above results,  SRc variables seems to be actually rare.  
> 
>     I suspect the number of SRc variables may have been underestimated
> because definite classification probably (I believe) needs spectroscopic
> confirmation.  Many SRb or SRa stars may have been classified based on
> light curves only, without information on luminosity classes.  I suspect
> many "missed" SRc stars may be found in SR stars without subclasses,
> or even in SRa or SRb stars without proper spectroscopic information.

I agree on this point.   Investigations on semi-regular and irregular 
variables seem to be not so intensive compared with those on other 
types of variables stars.   For this reason,  astrophysical information 
on these stars, like evolutionary stage, is very restricted.  

However,  as same as missed SRc stars, it is also possible that some 
other types of variables are miss-classified as SRc stars.  I wonder 
if miss-classification may not result to increase the number of SRc 
stars, rather may result to decrease it.  

I rather suspect that when astrophysical information is obtained for 
those red-pulsating stars,  the classification scheme itself may be 
changed.  In that case,  there will be no more SRc stars at all :-<, 
however, we then will know more precise number of pre-SN explosion 
candidates than present. :->   

I hope an active observer,  like Kato-san,  is intereseted in these kind of 
stars,  and observes these stars intensively.   It will be a way to help 
finding out 'happy waves'.  

regards, 

-- 
%  Toshihito ISHIDA, Ph. D., Astrophysicist                               %
%  Nishi-Harima Astronomical Observatory, Sayo-cho, Hyogo 679-53, JAPAN   %
%  Tel:     +81-790-82-3886 ext. 142      Telefax: +81-790-82-3514        %
%  e-mail: ishida@nhao.go.jp (usual) HQA01560@niftyserve.or.jp (off time) %

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