| dc.description.abstract | We present light curve analysis of the variable star, AZ Capriconi (BD-17 6128). A member of the Beta Pictoris moving star group, the star, of a spectral type of K6, is a known BY Draconi variable, i.e., with surface starspots and chromospheric activity to modulate the periodical brightness changes. We made use of the 18-year long (2001 to 2019) photometric observations taken by the All Sky Automated Survey (ASAS) to diagnose the long-term behavior in the light curve. Using the Lomb-Scargle periodicity algorithm, we confirmed the 3.4 day period previously known, but found no systematic period drift, as would be expected when starspots appear at different latitudes during a magnetic cycle, as observed in the Sun (aka, the Maunder diagram). AZ Cap continued to brighten in the 18 years covered by the observations. There were year-to-year amplitude variations, but no correlation was found with the light curve period. The sinusoidal amplitude of the data taken in 2015 indicated an effective spot radius of 0.38 of that of the star. It is likely that the X-ray emission and the starspot activity are caused by an unseen close-in, thereby synchronously rotating, companion to anchor the magnetic field. If so, the spot could extend to high latitudes or even to the pole. We infer that the AZ Cap has its rotation axis inclined no less than 32 degrees. | en_US |