A hybrid envelope-stripping mechanism for massive stars from supernova nebular spectroscopy

摘要

The final steps of the evolution of massive stars leading toa supernova explosion, in particular the mass-loss mechanism,is an important open problem in astrophysics. Strippedenvelopesupernovae (SESNe) are explosions of massivestars where a large amount of the outer envelope has beenstripped away before the explosion: types IIb, Ib and Ic inorder of increasing degree of envelope stripping. In thiswork, an analysis of late-time nebular spectra of SESNe is presented.The results show that the progenitors of Sne Iib andIb are indistinguishable except for the residual amount of theH-rich envelope. The progenitors of Sne Ic are distinctly differentin the nature of the carbon–oxygen (C+O) core, whichis interpreted to be more massive than in Sne Iib and Ib. Thesefindings strongly suggest that different mechanisms areresponsible for the removal of the outer H-rich envelope andthe deeper He-rich layer.