@article{3cdea2b3ed1441329742ecd96c283c78,
title = "SN 2017ens: The Metamorphosis of a Luminous Broadlined Type Ic Supernova into an SN IIn",
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 × 10 40 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. ",
author = "T-W Chen and C. Inserra and M. Fraser and Moriya, {T. J.} and P. Schady and T. Schweyer and A. Filippenko and Perley, {D. A.} and Ruiter, {A. J.} and Ivo Seitenzahl and J. Sollerman and F. Taddia and Anderson, {J. P.} and Foley, {R. J.} and A. Jerkstrand and C-C Ngeow and Y-C Pan and A. Pastorello and S. Points and Smartt, {S. J.} and Smith, {K. W.} and S. Taubenberger and P. Wienlan and Young, {D. R.} and S. Benetti and M. Berton and F. Bufano and P. Clark and {Della Valle}, M. and L. Galbany and A. Gal-Yam and M. Gromadzki and Gutierrez, {C. P.} and A. Heinze and E. Kankare and Kilpatrick, {C. D.} and H. Kuncarayakti and G. Leloudas and Z-Y Lin and K. Maguire and P. Mazzali and O. McBrien and Prentice, {S. J.} and A. Rau and A. Rest and Siebert, {M. R.} and B. Stalder and Tonry, {J. L.} and P-C Yu",
note = "T.W.C. acknowledges Thomas Kr{\"u}hler for the X-Shooter data reduction, Lin Yan and Claes Fransson for providing comparison spectra, Jason Spyromilio for useful discussions, Chien-Hsiu Lee and You-Hua Chu for coordinating observational resources, and funding from the Alexander von Humboldt Foundation. M.F. acknowledges the support of a Royal Society—Science Foundation Ireland University Research Fellowship. P.S. acknowledges support through the Sofia Kovalevskaja Award (Alexander von Humboldt Foundation). A.V.F. is grateful for the support of the TABASGO Foundation, the Christopher R. Redlich fund, and the Miller Institute for Basic Research in Science (U.C. Berkeley). A.J.R. and I.R.S. are supported by the Australian Research Council through grants FT170100243 and FT160100028, respectively. F.T. and J.S. acknowledge support from the KAW Foundation. S.J.S. acknowledges funding from the European Research Council Grant agreement #291222 and STFC grant ST/P000312/1. M.G. is supported by Polish National Science Centre grant OPUS 2015/17/B/ST9/03167. K.M. acknowledges support from the UK STFC through an Ernest Rutherford Fellowship and from a Horizon 2020 ERC Starting Grant (#758638). L.G. was supported in part by US NSF grant AST-1311862. C.P.G. acknowledges support from EU/FP7-ERC grant #615929. Z.Y.L., C.C.N., and P.C.Y. are grateful for funding from MoST (Taiwan) under grants 105-2112-M-008-002-MY3, 104-2923-M-008-004-MY5, and 106-2112-M-008-007. A.P. and S.B. are partially supported by PRIN-INAF 2017 {"}Toward the SKA and CTA era: discovery, localization, and physics of transient sources{"} (P.I.: Giroletti). A.G.-Y. is supported by the EU via ERC grant No. 725161, the Quantum Universe I-Core program, the ISF, the BSF Transformative program, and a Kimmel award. Part of the funding for GROND was generously granted from the Leibniz Prize to Prof. G. Hasinger (DFG grant HA 1850/28-1). Some observations were made with the Nordic Optical Telescope using ALFOSC. This publication has made use of data collected at Lulin Observatory, partly supported by MoST grant 105-2112-M-008-024-MY3. Some of the data presented herein were obtained at the W. M. Keck Observatory, which is operated as a scientific partnership among the California Institute of Technology, the University of California, and NASA; the observatory was made possible by the generous financial support of the W. M. Keck Foundation.",
year = "2018",
month = nov,
day = "10",
doi = "10.3847/2041-8213/aaeb2e",
language = "الإنجليزيّة",
volume = "867",
journal = "Astrophysical Journal Letters",
issn = "2041-8205",
publisher = "American Astronomical Society",
number = "2",
}