Ana P. Borisova, Valeri V. Hambaryan, John L. Innis
Bayesian statistical methods of Gregory-Loredo and the Bretthorst
generalization of the Lomb-Scargle periodogram have been applied for studying
activity cycles of the early K-type subgiant star CF Oct. We have used a ~45
year long dataset derived from archival photographic observations, published
photoelectric photometry, Hipparcos data series and All Sky Automated Survey
archive. We have confirmed the already known rotational period for the star of
20.16 d and have shown evidences that it has exhibited changes from 19.90 d to
20.45 d. This is an indication for stellar surface differential rotation.The
Bayesian magnitude and time--residual analysis reveals clearly at least one
long-term cycle. The cycle lenght's posterior distributions appear to be
multimodal with a pronounced peak at a period of 7.1 y with FWHM of 54 d for
time-residuals and at a period of 9.8 y with FWHM of 184 d for magitude data.
These results are consistent with the previously postulated cycle of 9+/-3
years.
View original:
http://arxiv.org/abs/1111.4155
No comments:
Post a Comment