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

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A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä

Date

2018-11-10

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en

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Astrophysical Journal Letters, Volume 867, issue 2

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.

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supernovae: general, supernovae: individual (SN 2017ens)

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Citation

Chen, T W, Inserra, C, Fraser, M, Moriya, T J, Schady, P, Schweyer, T, Filippenko, A V, Perley, D A, Ruiter, A J, Seitenzahl, I, Sollerman, J, Taddia, F, Anderson, J P, Foley, R J, Jerkstrand, A, Ngeow, C C, Pan, Y C, Pastorello, A, Points, S, Smartt, S J, Smith, K W, Taubenberger, S, Wiseman, P, Young, D R, Benetti, S, Berton, M, Bufano, F, Clark, P, Valle, M D, Galbany, L, Gal-Yam, A, Gromadzki, M, Gutiérrez, C P, Heinze, A, Kankare, E, Kilpatrick, C D, Kuncarayakti, H, Leloudas, G, Lin, Z Y, Maguire, K, Mazzali, P, McBrien, O, Prentice, S J, Rau, A, Rest, A, Siebert, M R, Stalder, B, Tonry, J L & Yu, P C 2018, ' SN 2017ens : The Metamorphosis of a Luminous Broadlined Type Ic Supernova into an SN IIn ', Astrophysical Journal Letters, vol. 867, no. 2, L31 . https://doi.org/10.3847/2041-8213/aaeb2e