A. Blanco et al., On the distance and mass-loss rate of carbon stars showing the silicon carbide emission feature, ASTRON ASTR, 357(2), 2000, pp. 515-519
The distances and the mass-loss rates of carbon stars are in general very p
oorly 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 more than an order of magnitude. In this
work we have evaluated these two important stellar parameters for a previo
usly selected sample of 55 carbon stars showing the 11.3 mu m band, commonl
y attributed to silicon carbide (SiC) grains. To perform the calculation we
have used the values of geometrical and physical parameters of these sourc
es obtained from the best fits of their observed spectra. Using the distanc
e values derived in this way and the 11.3 mu m band intensity, we have eval
uated the absolute band strength and we have found that, in agreement with
other authors, there is a correlation between this quantity and the mass-lo
ss rate. This correlation can be very useful to determine the mass-loss rat
e of other carbon stars not included in our sample, by means of the intensi
ty of the SiC band, without using the usual technique based on CO observati
ons. The same procedure can be conveniently applied to the same as well as
to other carbon stars, whose spectra will be available to the community in
the next future (i.e. the infrared spectra of sources observed by the Infra
red Satellite Observatory, ISO).