Details

Autor(en) / Beteiligte

• Terreran, G
• Jerkstrand, A
• Benetti, S
• Smartt, S. J
• Ochner, P
• Tomasella, L
• Howell, D. A
• Morales-Garoffolo, A
• Harutyunyan, A
• Kankare, E
• Arcavi, I
• Cappellaro, E
• Elias-Rosa, N
• Hosseinzadeh, G
• Kangas, T
• Pastorello, A
• Tartaglia, L
• Turatto, M
• Valenti, S
• Wiggins, P
• Yuan, F

Titel

The multifaceted Type II-L supernova 2014G from pre-maximum to nebular phase

Ist Teil von

• Monthly notices of the Royal Astronomical Society, 2016-10, Vol.462 (1), p.137-157

Ort / Verlag

London: Oxford University Press

Erscheinungsjahr

2016

Link zum Volltext

Quelle

Alma/SFX Local Collection

Beschreibungen/Notizen

• We present multiband ultraviolet, optical, and near-infrared photometry, along with visual-wavelength spectroscopy, of supernova (SN) 2014G in the nearby galaxy NGC 3448 (25 Mpc). 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 α after 100 d, which evolves to appear as a flat spectral feature linking H α and the [O i] 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⊙.