학술논문
SN 2017ens: The Metamorphosis of a Luminous Broad-lined Type Ic Supernova into an SN IIn
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Working Paper
Author
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.; Della Valle, M.; 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.
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Subject
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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 H-alpha and H-beta 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 H-alpha emission persisting at high luminosity (~3x10^40 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.
Comment: Accepted version in ApJL
Comment: Accepted version in ApJL