[vsnet-chat 3606] Perids of roughly one year

["Dahm, Michael" <marvin.siriuscorp@planet-interkom.de>]

Dear friends!

Studying the GCVS I found some years ago a funny distribution of the periods
of semiregular variables. It seems to be that this red giant distributed in
all directions of our Milky Way prefer a period of nearly 365 days or one
terrestical year. Of course this must be a result of spurious periods.

Now I can report about an investigation of two SRs on stardial images using
the photometric software package.

SY Aqr should have a period of 387 days which can not be confirmed. John
Graeves was able to find a well defined period of 220 day in my data and
also in Tycho-2 data.

DX Ser is listed in the GCVS with a 360 day period. Using FFT a period of
244 days can be found on stardial images.

A further case seems to be V1059 Cyg (P=372d according to GCVS). The star
has been observed visually by Ralf Meyer and his lightcurve can be
interpreted with a period of rounghly 300 days.

Checking periods of not well covered low amplitude semiregular variable
stars does not confirm reported period values. This seems to be an
interessting field for amateurs doing some kind of quality controll.


Michael Dahm
Email : marvin.siriuscorp@planet-interkom.de
Homepage : www.planet-interkom.de/marvin.siriuscorp/

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