Analysis of magnetic activity cycles in solar analogs using Solar - Stellar Spectrograph data

Abstract

The Solar-Stellar Spectrograph (SSS) Project includes frequent observations of 30 - 50 Sun-like stars to address a wide variety of questions regarding the nature of stellar magnetic activity cycles. The magnetic activity cycles of 18 stars in the SSS project are analyzed using the Lomb Scargle method of least-squares spectral analysis. Periodograms reveal that out of 18 stars, 9 stars have one magnetic cycle and 6 stars have two magnetic cycles, with periods ranging from 2 years to 17 years. The remaining stars show significant variability but without pronounced periodicity. Most of the detected cycles have a false alarm probability (FAP) well below 10-3 The results for a number of stars are compared and confirmed with earlier observations by Mount Wilson Observatory's project, published by Baliunas et. al. (1995). Four more stars are added to the plot of activity cycle period - rotational period relation by Bohm-Vitense (2006), and they all lie on either the active sequence or the inactive sequence. This result, together with the fact that several stars have two different cycles lying on different sequences, lends more evidence to the hypothesis that stars have multiple dynamos but are dominated by one of them.