DETECTION OF CIRCUMSTELLAR DUST SHELL AROUND THE SUPERGIANT TV GEMINORUM FROM MILLIARCSECOND RESOLUTION NEAR-INFRARED OBSERVATIONS

A lunar occultation of the M1 supergiant TV Gem has been observed in t he near infrared region at 2.2 mu m. A detailed analysis of the observ ed occultation light curve has been performed using two different redu ction methods permitting the circumstellar dust envelope to be directl y detected for the first time around TV Gem. The star has been resolve d to yield a uniform disk diameter of 4.9+/-0.3 milliarcseconds (mas) and the stellar effective temperature has been derived to be 3670+/-12 5 K. Its circumstellar dust envelope has a radius of similar to 20 R with star to shell Bur ratio of similar to 35 at 2.2 mu m. A simple ra diative transfer dust shell model constrained by our occultation obser vations, 9.7 mu m silicate emission feature strength and far IR excess seen in IRAS observations shows that the dust is probably restricted to two well separated dust shells - the inner shell is at a radial dis tance of similar to 20 R and the outer one is at similar to 500 R*. S poradic dust condensation in TV Gem as in the case of alpha Ori is sug gested.