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Date: Thu, 8 Apr 93 14:00:13 +0900 From: nomoto@apsun1.astron.s.u-tokyo.ac.jp Subject: II-L? >From wheel@astro.as.utexas.edu Thu Apr 8 12:23:31 1993 Date: Wed, 7 Apr 93 22:14:50 GMT From: wheel@astro.as.utexas.edu (Craig Wheeler) Subject: emission spectra of SN 1993J Here is the text of a circular we just submitted. Alejandro and I were editing it while he exposed tonight, 10 minutes ago, and the H-alpha emission is still there! Any bets on a II linear? Craig Brian Here is the text for a contribution to a circular: ******* J. C. Wheeler and A. Clocchiatti report that spectra from 500 to 850 nm obtained with the Imaging Grism Instrument on the 0.76 m telescope of McDonald Observatory on April 6.3 and 7.3 with a dispersion of 0.7 nm/pixel show the onset of strong H-alpha and distinct P-Cygni profiles. Crude reduction by division by a polynomial fit to a continuum of a DA dwarf (GRW+705824=EG102) reveals that the spectrum on April 7.3 has an emission peak at 654.5 nm of 29 nm FWHM with a broad minimum at 616.3 nm. The emission is roughly 6 times stronger than the absorption, appears to have sharp blue and red edges at 637 and 781 nm, respectively, and is asymmetric with a stronger red wing. This emission is most readily identified with H-alpha. The lack of deep absorption may indicate fluorescence from circumstellar material which may affect the location of the minimum. Another feature shows a P-Cygni profile with a maximum at 588.4 nm and a well-defined minimum at 566.5 nm. This feature could be either He I lambda 5876 or Na D. For He I, the minimum represents a velocity of 10,760 km/s. The emission is approximately as strong as the absorption. The peak also shows a narrow absorption line of interstellar Na D. Another broad mimimum appears at about 500 nm. Pending more accurate reduction, the spectrum resembles that of the Type II linear SN 1979C on May 28, 1979 (Branch et al. Ap. J. 244, 780, 1981) although identification of the nature of the event at this time is premature.
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