Multiple Dust Shells and Motions around IK Tauri as Seen by Infrared Interferometry

Abstract

A visibility curve of IK Tau has been measured with the ISI, an 11 km stellar interferometer, over a period of several years. Time variations in 11 km Ñux were also measured. The results indicate an approximately periodic distribution of dust shells around the star, with shells separated by 200È250 mas and a diameter of about 200 mas for the innermost shell. Some shell motion has been detected, and if velocities are the same as those measured for CO gas and OH masers, the motion implies that the distance to IK Tau is about 265 pc and that shells have been emitted at times separated by about 12 yr, which is considerably longer than the starÏs luminosity period of 470 days.