SN 2016coi/ASASSN-16fp: an example of residual helium in a typeIc supernova?. Issue 3 (11th May 2018)

• Record Type: Journal Article
• Authors: Prentice, S J; Ashall, C; Mazzali, P A; Zhang, J-J; James, P A; Wang, X-F; Vinkó, J; Percival, S; Short, L; Piascik, A; Huang, F; Mo, J; Rui, L-M; Wang, J-G; Xiang, D-F; Xin, Y-X; Yi, W-M; Yu, X-G; Zhai, Q; Zhang, T-M; Hosseinzadeh, G; Howell, D A; McCully, C; Valenti, S; Cseh, B; Hanyecz, O; Kriskovics, L; Pál, A; Sárneczky, K; Sódor, Á; Szakáts, R; Székely, P; Varga-Verebélyi, E; Vida, K; Bradac, M; Reichart, D E; Sand, D; Tartaglia, L;
• Is Part Of: Monthly notices of the Royal Astronomical Society. Volume 478:Issue 3(2018)
• Page Start: 4162
• Page End: 4192
• Publication Date: 2018-05-11
• Subjects: supernovae: individual- SN2016coi/ASASSN16-fp; Astronomy -- Periodicals; Periodicals; 520.5
• DOI: 10.1093/mnras/sty1223
• Languages: English
• ISSNs: 0035-8711

Abstract

ABSTRACT: The optical observations of Ic-4 supernova (SN) 2016coi/ASASSN-16fp, from ∼2 to ∼450 d after explosion, are presented along with analysis of its physical properties. The SN shows the broad lines associated with SNe Ic-3/4 but with a key difference. The early spectra display a strong absorption feature at ∼5400 Å which is not seen in other SNe Ic-3/4 at this epoch. This feature has been attributed to He i in the literature. Spectral modelling of the SN in the early photospheric phase suggests the presence of residual He in a C/O dominated shell. However, the behaviour of the He i lines is unusual when compared with He-rich SNe, showing relatively low velocities and weakening rather than strengthening over time. The SN is found to rise to peak ∼16 d after core-collapse reaching a bolometric luminosity of L p ∼3 × 10 42 erg s −1 . Spectral models, including the nebular epoch, show that the SN ejected 2.5–4 M⊙ of material, with ∼1.5 M⊙ below 5000 km s −1, and with a kinetic energy of (4.5–7) × 10 51 erg. The explosion synthesized ∼0.14 M⊙ of 56 Ni. There are significant uncertainties in E ( B − V )host and the distance, however, which will affect L p and M Ni . SN 2016coi exploded in a host similar to the Large Magellanic Cloud (LMC) and away from star-forming regions. The properties of the SN and the host-galaxy suggest that the progenitor had M ZAMS of 23–28 M⊙ and was stripped almost entirely down to its C/O core at explosion.