The ``Type IIb'' Supernova 1993J in M81: A Close Relative of Type Ib Supernovae

view Abstract Citations (197) References (45) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS The ``Type IIb'' Supernova 1993J in M81: A Close Relative of Type Ib Supernovae Filippenko, Alexei V. ; Matheson, Thomas ; Ho, Luis C. Abstract Spectra of SN 1993J at three epochs within the first 1.5 months after the explosion reveal the onset of a remarkable transformation. The prominent Hα emission line visible at early times became progressively weaker as P Cygni features of He I gradually appeared; SN 1993J is therefore a hydrogen-poor, helium-rich "Type IIb" supernova. The progenitor of SN 1993J was probably a reasonably massive star (initial mass 10-17 M_sun_) that transferred most, but not all, of its hydrogen envelope to a physically bound companion. We predict that many (>~6) months past maximum brightness, the spectrum of SN 1993J will closely resemble the late-time spectra of Type lb supernovae; it will be dominated by strong emission lines of [O I], [Ca II], and Ca II, with Hα very weak or absent. A similar metamorphosis has been clearly seen only in SN 1987K; however, since the development of He I lines could not be monitored, SN 1987K may have actually been Type IIc rather than Type IIb. SN 1993J demonstrates that SN 1987K was not a unique event. It strengthens the hypothesis that Type lb and Ic supernovae are not white dwarfs undergoing thermonuclear runaway. Rather, they are triggered by core collapse in massive, evolved stars that have lost their outer envelope of hydrogen (Ib) and perhaps helium as well (Ic), often through mass transfer in close binary systems. Thus, these objects are fundamentally related to Type II supernovae. Publication: The Astrophysical Journal Pub Date: October 1993 DOI: 10.1086/187043 Bibcode: 1993ApJ...415L.103F full text sources ADS | data products SIMBAD (9) NED (2)