SN 2017ens: The Metamorphosis of a Luminous Broadlined Type Ic Supernova into an SN IIn

Chen, T-W, Inserra, C, Fraser, M, Moriya, TJ, Schady, P, Schweyer, T, Filippenko, A, Perley, DA, Ruiter, AJ, Seitenzahl, I, Sollerman, J, Taddia, F, Anderson, JP, Foley, RJ, Jerkstrand, A, Ngeow, C-C, Pan, Y-C, Pastorello, A, Points, S, Smartt, SJ et al (2018) SN 2017ens: The Metamorphosis of a Luminous Broadlined Type Ic Supernova into an SN IIn. The Astrophysical Journal Letters, 867 (2). ISSN 2041-8205

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Abstract

We present observations of supernova (SN) 2017ens, discovered by the ATLAS survey and identified as a hot blue object through the GREAT program. The redshift z = 0.1086 implies a peak brightness of M g = −21.1 mag, placing the object within the regime of superluminous supernovae. We observe a dramatic spectral evolution, from initially being blue and featureless, to later developing features similar to those of the broadlined Type Ic SN 1998bw, and finally showing ~2000 km s−1 wide Hα and Hβ emission. Relatively narrow Balmer emission (reminiscent of a SN IIn) is present at all times. We also detect coronal lines, indicative of a dense circumstellar medium. We constrain the progenitor wind velocity to ~50–60 km s−1 based on P-Cygni profiles, which is far slower than those present in Wolf–Rayet stars. This may suggest that the progenitor passed through a luminous blue variable phase, or that the wind is instead from a binary companion red supergiant star. At late times we see the ~2000 km s−1 wide Hα emission persisting at high luminosity (~3 × 1040 erg s−1) for at least 100 day, perhaps indicative of additional mass loss at high velocities that could have been ejected by a pulsational pair instability.

Item Type: Article
Uncontrolled Keywords: 0201 Astronomical And Space Sciences
Subjects: Q Science > QB Astronomy
Q Science > QC Physics
Divisions: Astrophysics Research Institute
Publisher: American Astronomical Society
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Date of acceptance: 20 October 2018
Date of first compliant Open Access: 20 December 2018
Date Deposited: 20 Dec 2018 12:10
Last Modified: 04 Sep 2021 09:51
DOI or ID number: 10.3847/2041-8213/aaeb2e
URI: https://ljmu-9.eprints-hosting.org/id/eprint/9851
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