A. Blanco , A. Borghesi , S. Fonti & V. Orofino
Dipartimento di Fisica, Universita' di Lecce Via per Arnesano, C.P. 193, I-73100 Lecce, Italy
The distances and the mass-loss rates of carbon stars are in general very
poorly known. The various estimates of the distances, taken from the general
literature, show considerable discrepancies, while the evaluations of the
mass-loss rates can be in error by almost an order of magnitude.
In this work we have evaluated these two important stellar parameters for
a previously selected sample of carbon stars (55 sources) showing the 11.3
micron band, commonly attributed to silicon carbide grains. To perform
this evaluation we
have used the values of geometrical and physical parameters of these sources
obtained from the best fits of their IRAS spectra. Using the distance values
derived in this way and the 11.3 micron band intensity, we have calculated
the absolute band strenght P(SiC) and found that, in agreement with
other authors, there is a correlation between this quantity and the mass-
loss rate. This correlation can be very useful to determine the
mass-loss rate of other carbon stars not included in our sample, by means of
the intensity of the SiC band and without using data from CO observations.
The same procedure can be conveniently applied to the SWS-ISO
observations of carbon stars, which will be available to the community in
the near future.