Spectra of low-mass helium star models and the type IC supernova SN 1987M

view Abstract Citations (50) References (35) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Spectra of Low-Mass Helium Star Models and the Type IC Supernova SN 1987M Swartz, Douglas A. ; Filippenko, Alexei V. ; Nomoto, Ken'ichi ; Wheeler, J. C. Abstract Low-mass helium star models that reproduce the first 100 days of the light curve of the Type Ic SN 1987M are used in model atmosphere calculations. The resulting spectra are compared to observations from 60 to 140 days post-maximum. The small column depth to ^56^Co decay photons leads to strong optical helium lines at days after maximum which fade into the continuum for times t >~ 200 days while the He I 10830 A line remains a strong P-Cygni feature at all times examined. The lack of observed optical helium lines suggests SN 1987M has a low helium abundance with a total helium mass fraction not much in excess of ~7%. This suggests a significantly different evolutionary path from the helium-rich Type Ib SN 1984L. The effects on the theoretical spectrum of mixing the ejecta and/or artificially converting the helium to oxygen are also explored. In spite of very large departure coefficients, the predicted optical helium lines at late times are not strong enough to be identified in the current Type Ib or Type Ic data base. This provides an explanation for the similarity between optical spectra of these supernova subtypes at times exceeding about 200 days even if Type Ib contain substantial amounts of helium and Type Ic do not. The spectroscopic implications for Type Ic progenitor evolution, including the possible presence of a small amount of hydrogen in the ejecta, is discussed. Publication: The Astrophysical Journal Pub Date: July 1993 DOI: 10.1086/172831 Bibcode: 1993ApJ...411..313S Keywords: B Stars; Stellar Evolution; Stellar Interiors; Stellar Mass; Stellar Models; Stellar Spectra; Supernovae; Atmospheric Models; Light Curve; Stellar Atmospheres; Visible Spectrum; Astrophysics full text sources ADS | data products SIMBAD (4) NED (2)