[vsnet-chat 3678] re V Boo

[crawl@zoom.co.uk]

Ondrej Pejcha wrote:
>
>              Thanks all for help with V Boo. Very interesting sounds to
>              me decrease in amplitude only in the prominent 258 day
>              period. I would rather expect that some sort of obscuration
>              would also lower the amplitude of shorter 137 day period,
>              i.e. preserving the amplitude ratio. Could this solve adding
>              third period, with value very close to 258 day? This would
>              cause very slow beating up between these two periods,
>              137days period's amplitude remaining unchanged. I've put at
>              http://vsnet.volny.cz/opejcha/vboo/vboosim.gif a simulation,
>              how would look lightcurve of hypothetic object with three
>              periods: 258, 257 and 137 days and with amplitudes in ratio
>              1:1:0.19.

Very interesting!!!

A lot of people mention things like two close periods for long term
periodicity changes in LPV periods, and they never seem to get anywhere much.

HOWEVER, in this instance you bring up something very interesting.

You'll have noticed that there is also a 259 to 260 day period in the
BAAVSS V Boo data of about 0.3 magnitudes semi-amplitude that wouldn't go
away.  You can just see it on the fouriergram in the article.

At the time I probably just assumed that it was an interval of time when V
Boo's 258 day period had drifted a bit.  As you probably know, in a DFT
plot _all_ the time periods evident in a long run of data are shown
superimposed, with no clues as to whether these periods were long lasting,
transitory or whatever.

So, possibly try the same thing with periods of 260 days, 257.8 and 137
days in ratios of 0.3:0.8:0.1 or whatever.  I'm afraid I am not certain
what the exact value is for the the 259-260 day period, and I apparently
didn't document it too well in the article.

I suggest you redo your DFT at a higher cycles per day resolution and see
if you can find a period around 260 days separate to the 258 day one, and
use that for your beat test.

Cheers

John

John Greaves
UK

PS, will this beat effect lead to an increase in amplitude eventually, in a
cyclical sort of way, cos if it will it is due to start increasing in
amplitude again soon, possibly, looking at the lightcurve[????]

A nice lpv for being observed more than twice a month, BTW ;^)

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