Type II supernova 1979c in M100 and the distance to the Virgo cluster

摘要: Optical spectra of supernova 1979c in M100 obtained between 1979 April 22 and November 24 are presented discussed detail. Interstellar lines originating from both our Galaxy examined. Synthetic computed using a blackbody photosphere pure scattering expanding atmosphere successfully model the continua P Cygni profiles up to May 28. The H..cap alpha.. profile is not explained by resonance scattering, but collisional excitation may be responsible for net emission this line as well Mg II lambda2798 seen IUE spectra. Velocities temperatures derived combined with photometric data determine distance Baade method. We find 23 +- 3 (rms) Mpc, corresponding Hubble parameter about 60 km s/sup -1/ Mpc/sup -1/. precursor star seems have had an extended circumstellar envelope, mass estimated been at least 9 M/sub sun/. chemical composition standpoint H region observations synthetic