DUST ENVELOPE PARAMETERS OF THE CARBON STAR-T CANCRI FROM THE DATA ONENERGY AND BRIGHTNESS DISTRIBUTIONS

A model of the dust envelope of the carbon star T Cnc was calculated u sing information on the spectral energy distribution and on brightness distribution in the near infrared. The model consists of a central st ar radiating like a black body and surrounded by a spherically symmetr ical envelope of particles of amorphous carbon, with radii of 0.05 mic rons. The envelope has a sharp inner boundary at 2.8 stellar radii fro m the system's center, with a simple power law of dust particle densit y distribution (is-proportional-to r-2). We obtained the following mod el parameters: effective temperature, 2430 +/- 60 K; optical depth of the envelope for the wavelength 2.20 microns, 0.027 +/- 0.003; dust te mperature at the inner boundary of the envelope, 1250 +/- 30 K; and du st particle concentration at this boundary, almost-equal-to 1.8 x 10(- 4) cm-3.