[vsnet-chat 3671] Re: V Boo

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

> When I performed a simple DFT on data to find a period, I
> freezed up: the Fourier spectrum showed two clearly evident
> periods with values 258 days (same as GCVS and Kiss et al.)
> and also 131 days. Quick look at averaged lightcurve showed
> that these is caused by well pronounced hump on ascending
> branch, which recently developed into double maximum.

Ondrej,

V Boo isn't on my list for obvious reasons, but there are similar 
specimens in the southern sky. For example R Cen and R Nor have distinct 
double periods but are classed as M. Recent speculation about T Cen 
suggests it may be M with two periods, one of which fades in and out of 
detection. L2 Pup (SR) ranges between episodes of Mira-like regularity 
and complete incoherence. S Car (M) often exhibits lumps on its 
lightcurve like an SR. And so on....

The distinction between SR and M is crumbling, as we find more and more 
stars unexpectedly "changing sides" or "misbehaving" like the above 
examples. I reckon that the classes M and SR should be viewed as two 
(temporary) aspects of the same phenomenon – if they are not already.

As to where the L class fits in I can only speculate. But to continue the 
example of L2 Pup, if you only had the light curve for the 1998-1999 
seasons to examine, you would probably have concluded that this star was 
a low-amplitude irregular.

To quote a Bhuddist friend of mine: "all things are impermanent". So keep 
watching.


Cheers,
Fraser Farrell

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