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Session 6 - Novae and Supernovae.
Display session, Monday, June 08
We use the parameterized spectrum-synthesis code SYNOW to analyze optical spectra of the unusual supernova 1997ef. SN 1997ef was discovered in late November, and its spectra before and around the time of maximum light were peculiar. But spectra obtained in January resembled the spectra of the Type Ic SN 1994I when it was at an earlier phase, showing P Cygni profiles of lines of Fe II, Ca II, O I, Ti II, Na I, Si II, and C II. We have explored several interpretations of the early spectra. When a traditional steep density gradient for the line forming layers is used, the spectra can be fit only by invoking high velocities at the photosphere, as well as lines of unexpected ions such as Mn II and Co II. When a shallow density gradient is used, the required velocities at the photosphere are reduced as would be expected, and the spectra can be fit without invoking unusual ions. In either case, however, simple estimates of the kinetic energy carried by the line--forming layers come out surprisingly high.
Program listing for Monday