Optical Spectra of SN 1993J During the First Week
Session 39 -- SN1993J, SN1978K and SN1987A
Display presentation, Thursday, January 13, 9:30-6:45, Salons I/II Room (Crystal Gateway)

## [39.01] Optical Spectra of SN 1993J During the First Week

R.A.Finn, R.A.Fesen, J.D.Darling, J.R.Thorstensen (Dartmouth), G.Worthey (U of Mich)

Optical spectra of SN1993J in M81 are presented for each night from \mbox{March 31.1 1993 UT} to \mbox{April 7.1 1993 UT} with wavelength coverage from \mbox{4400 $\rm\AA$} to \mbox{8200 $\rm\AA$} at \mbox{4 $\rm\AA$} resolution. Emission features near 4950, 5860, and \mbox{6560 $\rm\AA$} begin to appear on March 31.1 and continue to rise throughout the first week. Faint emission near \mbox{6370 $\rm\AA$}, probably due to \mbox{[Fe X] 6374 $\rm\AA$}, is detected on \mbox{April 1.1} and fades by \mbox{April 2.2}. This fading suggests a radius of 0.001 pc for the [Fe X] emitting region, assuming a SN expansion velocity of \mbox{10,000 km s$^{-1}$.} The H$\alpha$ feature at 6560 $\rm\AA$ extends from 6350 to 6800 $\rm\AA$ corresponding to velocities of \mbox{$\rm\pm$ 10,000 km s$^{-1}$.} A slight dip centered at \mbox{6516 $\rm\AA$} is seen on the H$\alpha$ emission peak beginning \mbox{April 2.2}, and grows deeper through the first week. If the feature at \mbox{5860 $\rm\AA$} is due to \mbox{He I} $\rm5876\AA$, the corresponding Doppler width is \mbox{$\rm\pm$ 12,000 km s$^{-1}$.} Possible absorption features blueward of H$\alpha$ and \mbox{He I} appear on \mbox{April 3.1}, as well as emission near \mbox{ 5100 $\rm\AA$}. On April 4.1 the feature at \mbox{4950 $\rm\AA$} resolves into two peaks at 4797 and \mbox{4909 $\rm\AA$}, which we attribute to blueshifted \mbox{Fe II} 4924, \mbox{5018 $\rm\AA$} lines. On April 5.1, the emission at \mbox{5100 $\rm\AA$} can be resolved into two peaks centered at \mbox{5073 $\rm\AA$} and \mbox{5226 $\rm\AA$.} Discussion of these data will be presented.