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

: Qiliang Fang, Keiichi Maeda, Hanindyo Kuncarayakti, Fengwu Sun, Avishay Gal-Yam

Publisher: NATURE PUBLISHING GROUP

: 2019

: Nature Astronomy

: NATURE ASTRONOMY

: NAT ASTRON

: 3

: 5

: 434

: 439

: 6

: 2397-3366

DOI: https://doi.org/10.1038/s41550-019-0710-6

The final steps of the evolution of massive stars leading to a supernova explosion, in particular the mass-loss mechanism, is an important open problem in astrophysics. Strippedenvelope supernovae (SESNe) are explosions of massive stars where a large amount of the outer envelope has been stripped away before the explosion: types IIb, Ib and Ic in order of increasing degree of envelope stripping(1-3). In this work, an analysis of late-time nebular spectra of SESNe is presented. The results show that the progenitors of SNe IIb and lb are indistinguishable except for the residual amount of the H-rich envelope. The progenitors of SNe Ic are distinctly different in the nature of the carbon-oxygen (C+O) core, which is interpreted to be more massive than in SNe IIb and Ib. These findings strongly suggest that different mechanisms are responsible for the removal of the outer H-rich envelope and the deeper He-rich layer.