[vsnet-chat 3680] Re: V Boo

["Ondrej Pejcha" <opejcha@volny.cz>]

John Greaves wrote:

> 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 tried it. It produces something similar to previous
figure, but decrease in amplitude was very small, 0.3 mag
and the "minimum amplitude and maximum beating up" region
was situated in the middle of the plot, i.e. occured after
16000 days. This implies that maximum difference between two
close periods is ~1 day, which provides maximum beat up
effect at present. According to the recent MEDUZA data,
amplitude of 258 day period is about 0.32 mag and 0.25 mag
of the 137 d period, respectively. If the maximum beat up
occurs at present, the difference of amplitude between the
two close periods is 0.3 mag.

> 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.

I've done it again with MEDUZA data (I have nothing else).
There was nothing in the region of question. But MEDUZA data
covers small amount of time. However, I wonder if the close
component is real. One may suggest that the close component
is only some type of "reaction" of DFT on decreasing
amplitude. If you substract from dataset with decreasing
amplitude sine wave with mean amplitude of the whole
dataset, then you get sine with period equal to the
substracted sine and amplitude firstly decreasing, then zero
and then increasing. Now I'm working on modification of
programme which produced previous simulation to incorporate
type of sine that decreases its amplitude intrinsically,
i.e. not using close component. Picture will explain it
better than my poor English.

> 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[????]

If it is really caused by close component, then it will
start increasing amplitude. But I'm not happy with waiting
next 50 years for confirmation...

Best regards,

Ondrej Pejcha

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