NARROW FEATURES IN THE EARLY SPECTRUM OF SN-1993J

High resolution spectra of SN 1993J obtained on March 31.0, only three days past outburst, show narrow emission lines due to Halpha, HeII la mbda4686 and to the high ionization [FeX]lambda6374 and [FeXIV] lambda 5303. The latter, to our knowledge, has never been identified before i n SN spectra. The FWHM of the recombination lines indicate that the em itting gas has velocities approximately 170 km s-1 which seems too lar ge to be attributed to a normal stellar wind. The detection of narrow lines soon after outburst and their disappearance one week later, indi cate that the circumstellar gas ii confined close to the exploding sta r (R less-than-or-equal-to 4 x 10(15) cm). The coronal lines are proba bly generated in the CSM heated by the radiation emerging from the sho cked regions. A kinetic temperature of approximately 2.5 x 10(6)-degre es K is derived from the line widths. The interstellar NaID absorption shows a multiple component structure in agreement with previous repor ts. Its equivalent width suggests a moderately high reddening, 0.2 les s-than-or-equal-to E(B - V) less-than-or-equal-to 0.8 whereas the uppe r limits to the 5780 angstrom and 5797 angstrom DIBs indicate a redden ing E(B - V) less-than-or-equal-to 0.4.