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Astron. Astrophys. 319, 260-266 (1997)

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Detection of circumstellar dust shell around the supergiant TV Geminorum from milliarcsecond resolution near-infrared observations

Sam Ragland , T. Chandrasekhar and N.M. Ashok

Physical Research Laboratory, Navrangpura, Ahmedabad-380 009, India (e-mail: sam@prl.ernet.in)

Received 25 October 1995 / Accepted 22 July 1996

Abstract

A lunar occultation of the M1 supergiant TV Gem has been observed in the near infrared region at 2.2µm. A detailed analysis of the observed occultation light curve has been performed using two different reduction methods permitting the circumstellar dust envelope to be directly detected for the first time around TV Gem. The star has been resolved to yield a uniform disk diameter of 4.9 [FORMULA] 0.3 milliarcseconds (mas) and the stellar effective temperature has been derived to be 3670 [FORMULA] 125 K. Its circumstellar dust envelope has a radius of [FORMULA] 20 [FORMULA] with star to shell flux ratio of [FORMULA] 35 at 2.2µm. A simple radiative transfer dust shell model constrained by our occultation observations, 9.7µm 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 distance of [FORMULA] 20 [FORMULA] and the outer one is at [FORMULA] 500 [FORMULA]. Sporadic dust condensation in TV Gem as in the case of [FORMULA] Ori is suggested.

Key words: stars: TV Gem – circumstellar matter – supergiants – stars: fundamental parameters – infrared: stars

Send offprint requests to: S. Ragland

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© European Southern Observatory (ESO) 1997

Online publication: July 3, 1998
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