HR 1362 - A test case for stellar dynamo theories

Abstract

An analysis of 11 yr of photometry of HR 1362 = EK Eri has shown a well-established photometric period of 335 days. This confirms an earlier period determination of about 310 days from 3 yr of APT data and is consistent with a new v sin i determination of 2 + or - 2 km/s. Recent Ca II H and K observations show moderately strong H and K emission lines at a flux level of log F prime (K) of about 6.5 ergs sq m/s. If the photometric period is interpreted as the rotation period, this surface flux is more than one order of magnitude larger than what can be expected from empirical activity versus rotation relationships. The spectrum and the U-B and B-V colors are consistent with a single G8 III-IV spectral classification, while the V-R and V-I values indicate a small color excess, typical of chromospherically active stars.