The spectacular evolution of Supernova 1996al over 15 yr: A low-energy explosion of a stripped massive star in a highly structured environment
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Fecha
2016-03
Profesor/a Guía
Facultad/escuela
Idioma
en
Título de la revista
ISSN de la revista
Título del volumen
Editor
Oxford University Press
Nombre de Curso
Licencia CC
Licencia CC
Resumen
Spectrophotometry of SN 1996al carried out throughout 15 yr is presented. The early pho tometry 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 superim posed 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 be fore 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.
Notas
Indexación: Scopus.
Palabras clave
Supernovae: General
Citación
Monthly Notices of the Royal Astronomical Society. Volume 456, Issue 3, Pages 3296 - 3317. 1 March 2016
DOI
10.1093/mnras/stv2811