[vsnet-chat 1805] Re: Yellow Alert from Eta Carinae

["Fraser Farrell" <fraserf@dove.net.au>]

G'day all,

On Wed, 21 Apr 1999 01:27:36 -0500, Bish Ishibashi wrote:
> As we noted in IAUC 7146, Eta Carinae has been increasing its
> brightness at a unusual rate in the optical wavebands.
[snipped]
> and Whitelock at SAAO, and Metcalfe UT Austin) shows the larger
> increase and gives an estimated V magnitude of 5.25, indicating
> nearly the rate of change of a -0.3 mag per year since the end of
> 1997. This is by far the largest, and the most rapid brightening
> of Eta Car in the recent history of this star. 

I've been getting visual magnitudes of 5.1-5.2 for the last couple of 
months.  To continue the historical context, last time Eta Car was 
this bright, my place was unexplored territory inhabited by the 
Ngarrindijeri aboriginies, gold had just been discovered in the 
colony of New South Wales, and John Tebbutt was still basking in the 
fame of discovering the Great Comet of 1831.


> I understand, from Frasier's comment for a long ago, that Eta Carinae
> is a difficult star to observe for novice amateurs because of many
> reasons (1., the "homunculus" nebula is bright, and 2., the spectrum
> is strongly contaminated by EMISSION lines and appear reddish due to
> a strong H-Alpha emission line formed in the wind, perhaps, and etc).

I think, now that it has brightened, it is an easier target. The 
homunculus is contributing relatively less light than before.  On 
moonless nights Eta Car is now visible to the naked eye, and in 7x50 
binoculars it has a definite orange-red tint.  

I presume that the brightening is due to the thinning of the surrounding 
dust shell(s) as they expand.  However, I'm eagerly awaiting the day 
when I need to wear sunglasses to observe Eta Car, and use Venus as a 
"comparison star" ;-)




cheers,
Fraser Farrell

http://vsnet.dove.net.au/~fraserf/

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