Re: First Variable Star?

[Fraser Farrell <fraser@trilobytes.com.au>]

On Fri, 22 Mar 2002 13:38, Tom Droege wrote:
> Simbad shows a star at:
>
> RA 7h 56m 16.26s +5d 49m 28.4s    B = 8.41   V =  8.43  Type B9
>
> How do I tell if it is a variable from the Simbad data?


Tom,

Do a Simbad search for all objects within 10 to 20 arcminutes of your 
coordinates. Many variables' positions are poorly recorded (or downright 
wrong) so don't expect bulls-eyes. Then check out the detailed Simbad 
listing for each object. Sometimes there are indications of possible 
variability buried in the data from the various sources, even if the star 
is not actually listed in the GCVS or NSV catalogues.

Your candidate corresponds well to HD 64885 which is not known to be 
variable. However a lot of the B-type stars are known to be short-period 
low amplitude variables (typically of the "Beta Cepheii" class). And the 
vague boundary between "variable star" and "constant star" tends to cause 
religious wars from time to time. A 0.06 mag variation is getting close to 
no-man's-land I think....

But assuming it's not a camera fault or data reduction error, or a bogus 
caused by thin cloud and/or changing airmass, then you may indeed be onto 
a Discovery ;-)

Usual procedure at this point is to gather enough data to produce some 
sort of lightcurve; and then publish a note in the IBVS. To bolster 
confidence, you should also analyse your results for the known variables 
(if any) in the same images.


cheers,


-- 

Fraser Farrell

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