The spectacular evolution of Supernova 1996al over 15 yr: A low-energy explosion of a stripped massive star in a highly structured environment

S. Benetti, N. N. Chugai, V. P. Utrobin, E. Cappellaro, F. Patat, A. Pastorello, M. Turatto, G. Cupani, R. Neuhäuser, N. Caldwell, G. Pignata, L. Tomasella

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15 Citas (Scopus)

Resumen

Spectrophotometry of SN 1996al carried out throughout 15 yr is presented. The early photometry suggests that SN 1996al is a linear Type II supernova, with an absolute peak of MV ~ -18.2 mag. Early spectra present broad asymmetric Balmer emissions, with superimposed narrow lines with P-Cygni profile, and He I features with asymmetric broad emission components. The analysis of the line profiles shows that the H and He broad components form in the same region of the ejecta. By day +142, the Hα profile dramatically changes: the narrow P-Cygni profile disappears, and the Hα is fitted by three emission components that will be detected over the remaining 15 yr of the supernova (SN) monitoring campaign. Instead, the He I emissions become progressively narrower and symmetric. A sudden increase in flux of all He I lines is observed between 300 and 600 d. Models show that the SN luminosity is sustained by the interaction of low-mass (~1.15 M) ejecta, expelled in a low kinetic energy (~1.6 × 1050 erg) explosion, with highly asymmetric circumstellar medium. The detection of Hα emission in pre-explosion archive images suggests that the progenitor was most likely a massive star (~25 M ZAMS) that had lost a large fraction of its hydrogen envelope before explosion, and was hence embedded in a H-rich cocoon. The low-mass ejecta and modest kinetic energy of the explosion are explained with massive fallback of material into the compact remnant, a 7-8-M black hole.

Idioma originalInglés
Páginas (desde-hasta)3296-3317
Número de páginas22
PublicaciónMonthly Notices of the Royal Astronomical Society
Volumen456
N.º3
DOI
EstadoPublicada - 1 mar 2016

Áreas temáticas de ASJC Scopus

  • Astronomía y astrofísica
  • Ciencias planetarias y espacial

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    Benetti, S., Chugai, N. N., Utrobin, V. P., Cappellaro, E., Patat, F., Pastorello, A., Turatto, M., Cupani, G., Neuhäuser, R., Caldwell, N., Pignata, G., & Tomasella, L. (2016). The spectacular evolution of Supernova 1996al over 15 yr: A low-energy explosion of a stripped massive star in a highly structured environment. Monthly Notices of the Royal Astronomical Society, 456(3), 3296-3317. https://doi.org/10.1093/mnras/stv2811