  We report the detection of a very narrow P Cygni profile on top of the broad
emission Ha and Hb lines of the Type IIn Supernova 1997eg. A similar feature
has been detected in SN 1997ab (Salamanca et al. 1998), SN 1998S (Meikle &
Geballe 1998, Fassia et al. 2001) and SN 1995G (Filippenko & Schlegel 1995).
The detection of the narrow P Cygni profile indicates the existence of a dense
circumstellar material (CSM) into which the ejecta of the supernova is
expanding. From the analysis of the spectra of SN 1997eg we deduce (a) that
such CSM is very dense (n ~ 5x10^7 cm^-3), (b) that has a low expanding
velocity of about 160 \kms. The origin of such dense CSM can be either a very
dense progenitor wind (dotM ~ 10^-2 solar masses per year) or a circumstellar
shell product of the progenitor wind expanding into a high pressure
environment.
