[vsnet-chat 5692] Re: re CK Ori and W Ori tonight

[jg@jgws.freeisp.co.uk]

Sebastian Otero noted and opined :

> And John:
> 
> > Also to be noted is that W Ori was likely at maximum in its long cycle
> > roughly a year ago, too.  I estimate the long cycle as being about 2360
> > days using AFOEV data to hand, whilst Houk in AJ 68, 253 (1963)
> > [adsabs.harvard.edu for downloadable copy] reckoned 2450 days.  I
> > derived time of 'twin maximum' from the same AFOEV data, and the last
> > subsequent time of long cycle maximum would have been about 330 days
> > ago.
> 
> However, the shape of my lightcurve suggest W Ori is getting brighter and
> that when I first observed it in January 1999 it was brighter (V= 5.5)
> than it was after that and up to now. It's strange that I can find a deep
> minimum exactly 330 days ago (V= 6.6) not a maximum. Most of the observers
> noted it and that's why we started a discussion on this star, so maybe
> John meant minimum instead of maximum?

John most assuredly did.  As noted in chat 5690, I screwed up through
neglecting to double check that the program I was using was obeying
standard axes conventions re mag display. It wasn't, the reverse in
fact.


Of interest to me is the tightness of this result for the long cycle. 
The point I picked as an evident deep minimum (eventually, after first
mistaking it for a high maximum) from the AFOEV data was about JD
2442850, and the long cycle length from the same data was 2360 days,
giving me that 330 days ago prediction, which Sebastian confirms.


Such tightness of fit that can occur from time to time for this sort of
thing, when there is enough data, is why I always lean towards something
as regular as rotation as an explanation, coupled with stable asymmetry
and probably the line of sight effect of axial inclination being
responsible for amplitude of phenomenon.

Well, it _sounds_ a simple enough mechanism ;)

Cheers

John

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