Mon. Not. R. Astron. Soc., 482, 2750-2769 (2019/January-2)
Signatures of an eruptive phase before the explosion of the peculiar core-collapse SN 2013gc.
REGUITTI A., PASTORELLO A., PIGNATA G., BENETTI S., CAPPELLARO E., TURATTO M., AGLIOZZO C., BUFANO F., MORRELL N.I., OLIVARES F.E., REICHART D.E., HAISLIP J.B., KOUPRIANOV V., SMARTT S.J. and CIROI S.
Abstract (from CDS):
We present photometric and spectroscopic analysis of the peculiar core-collapse supernova (SN) 2013gc, spanning 7 yr of observations. The light curve shows an early maximum followed by a fast decline and a phase of almost constant luminosity. At +200 d from maximum, a brightening of 1 mag is observed in all bands, followed by a steep linear luminosity decline after +300 d. In archival images taken between 1.5 and 2.5 yr before the explosion, a weak source is visible at the supernova location, with mag ≃20. The early supernova spectra show Balmer lines, with a narrow (∼560 km s–1) P-Cygni absorption superimposed on a broad (∼3400 km s–1) component, typical of Type IIn events. Through a comparison of colour curves, absolute light curves, and spectra of SN 2013gc with a sample of supernovae IIn, we conclude that SN 2013gc is a member of the so-called Type IId subgroup. The complex profile of the H α line suggests a composite circumstellar medium geometry, with a combination of lower velocity, spherically symmetric gas, and a more rapidly expanding bilobed feature. This circumstellar medium distribution has been likely formed through major mass-loss events that we directly observed from 3 yr before the explosion. The modest luminosity (MI ∼ -16.5 near maximum) of SN 2013gc at all phases, the very small amount of ejected 56Ni (of the order of 10–3 M☉), the major pre-supernova stellar activity, and the lack of prominent [O I] lines in the late-time spectra support a fall-back core-collapse scenario for the massive progenitor of SN 2013gc.
© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society
supernovae: general - supernovae: individual: (SN 2013gc, SN 1994aj, SN1996al, SN1996L, SN2000P)
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