TY - JOUR
T1 - The multifaceted Type II-L supernova 2014G from pre-maximum to nebular phase
AU - Terreran, G.
AU - Jerkstrand, A.
AU - Benetti, S.
AU - Smartt, S. J.
AU - Ochner, P.
AU - Tomasella, L.
AU - Howell, D. A.
AU - Morales-Garoffolo, A.
AU - Harutyunyan, A.
AU - Kankare, E.
AU - Arcavi, I.
AU - Cappellaro, E.
AU - Elias-Rosa, N.
AU - Hosseinzadeh, G.
AU - Kangas, T.
AU - Pastorello, A.
AU - Tartaglia, L.
AU - Turatto, M.
AU - Valenti, S.
AU - Wiggins, P.
AU - Yuan, F.
N1 - Publisher Copyright:
© 2016 The Authors.
PY - 2016/10/11
Y1 - 2016/10/11
N2 - We present multiband ultraviolet, optical, and near-infrared photometry, along with visualwavelength spectroscopy, of supernova (SN) 2014G in the nearby galaxy NGC 3448 (25Mpc). The early-phase spectra show strong emission lines of the high ionization species He II/N IV/C IV during the first 2-3 d after explosion, traces of a metal-rich circumstellar material (CSM) probably due to pre-explosion mass-loss events. These disappear by day 9 and the spectral evolution then continues matching that of normal Type II SNe. The post-maximum light curve declines at a rate typical of Type II-L class. The extensive photometric coverage tracks the drop from the photospheric stage and constrains the radioactive tail, with a steeper decline rate than that expected from the 56Co decay if γ-rays are fully trapped by the ejecta. We report the appearance of an unusual feature on the blue side of H a after 100 d, which evolves to appear as a flat spectral feature linking H a and the [OI] doublet. This may be due to interaction of the ejecta with a strongly asymmetric, and possibly bipolar CSM. Finally, we report two deep spectra at ~190 and 340 d after explosion, the latter being arguably one of the latest spectra for a Type II-L SN. By modelling the spectral region around the [Ca II], we find a supersolar Ni/Fe production. The strength of the [O I] λλ6300,6363 doublet, compared with synthetic nebular spectra, suggests a progenitor with a zero-age main-sequence mass between 15 and 19 M.
AB - We present multiband ultraviolet, optical, and near-infrared photometry, along with visualwavelength spectroscopy, of supernova (SN) 2014G in the nearby galaxy NGC 3448 (25Mpc). The early-phase spectra show strong emission lines of the high ionization species He II/N IV/C IV during the first 2-3 d after explosion, traces of a metal-rich circumstellar material (CSM) probably due to pre-explosion mass-loss events. These disappear by day 9 and the spectral evolution then continues matching that of normal Type II SNe. The post-maximum light curve declines at a rate typical of Type II-L class. The extensive photometric coverage tracks the drop from the photospheric stage and constrains the radioactive tail, with a steeper decline rate than that expected from the 56Co decay if γ-rays are fully trapped by the ejecta. We report the appearance of an unusual feature on the blue side of H a after 100 d, which evolves to appear as a flat spectral feature linking H a and the [OI] doublet. This may be due to interaction of the ejecta with a strongly asymmetric, and possibly bipolar CSM. Finally, we report two deep spectra at ~190 and 340 d after explosion, the latter being arguably one of the latest spectra for a Type II-L SN. By modelling the spectral region around the [Ca II], we find a supersolar Ni/Fe production. The strength of the [O I] λλ6300,6363 doublet, compared with synthetic nebular spectra, suggests a progenitor with a zero-age main-sequence mass between 15 and 19 M.
KW - General
KW - supernovae
UR - http://www.scopus.com/inward/record.url?scp=84988693377&partnerID=8YFLogxK
U2 - 10.1093/mnras/stw1591
DO - 10.1093/mnras/stw1591
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AN - SCOPUS:84988693377
SN - 0035-8711
VL - 462
SP - 137
EP - 157
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 1
ER -