Periodic Brightness Modulation of the T Tauri Star V716 Per Based on Optical and Infrared Photometry

Abstract

Results of long-term optical and near infrared observations (VRI and JHK bands, respectively) of the T Tauri star V716 Per are reported. The previously discovered period of the optical brightness variation of the star is confirmed. Our data yield a period of 7.50 days. The period is stable over the entire interval of our observations (about 12 years), although the shape and amplitude of the brightness phase curves varied from season to season. For the first time it is shown that this period is also present in the variations of the JHK infrared fluxes. It is also shown that besides the short period, a slow wave with a duration comparable to the interval of our observations appears in the variations of the star’s brightness. Two models of the star’s variability are considered for analyzing its photometric behavior: (a) surface activity owing to the existence of cold (magnetic) spots on the star and (b) AA Tau type variability caused by periodic eclipsing of the star by its own circumstellar disk, the inner region of which is warped because of interactions with the star’s magnetosphere. The latter model matches the optical observations better. In the infrared, that model only provides a partial fit to the observed variability. In the K band, the major contribution to the variability is from changes in the luminosity of the inner disk caused by fluctuations in the accretion rate.