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A UV resonance line echo from a shell around a hydrogen-poor superluminous supernova

Lunnan, R. and Fransson, C. and Vreeswijk, P. M. and Woosley, S. E. and Leloudas, G. and Perley, D. A. and Quimby, R. M. and Yan, Lin and Blagorodnova, N. and Bue, B. D. and Cenko, S. B. and De Cia, A. and Cook, D. O. and Fremling, C. U. and Gatkine, P. and Gal-Yam, A. and Kasliwal, M. M. and Kulkarni, S. R. and Masci, F. J. and Nugent, P. E. and Nyholm, A. and Rubin, A. and Suzuki, N. and Wozniak, P. (2018) A UV resonance line echo from a shell around a hydrogen-poor superluminous supernova. Nature Astronomy, 2 (11). pp. 887-895. ISSN 2397-3366.

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Hydrogen-poor superluminous supernovae (SLSN-I) are a class of rare and energetic explosions that have been discovered in untargeted transient surveys in the past decade. The progenitor stars and the physical mechanism behind their large radiated energies (about 10^(51) erg or 10^(44) J) are both debated, with one class of models primarily requiring a large rotational energy and the other requiring very massive progenitors that either convert kinetic energy into radiation through interaction with circumstellar material (CSM) or engender an explosion caused by pair-instability (loss of photon pressure due to particle–antiparticle production). Observing the structure of the CSM around SLSN-I offers a powerful test of some scenarios, although direct observations are scarce. Here, we present a series of spectroscopic observations of the SLSN-I iPTF16eh, which reveal both absorption and time- and frequency-variable emission in the Mg IIresonance doublet. We show that these observations are naturally explained as a resonance scattering light echo from a circumstellar shell. Modelling the evolution of the emission, we infer a shell radius of 0.1 pc and velocity of 3,300 km s−1, implying that the shell was ejected three decades before the supernova explosion. These properties match theoretical predictions of shell ejections occurring because of pulsational pair-instability and imply that the progenitor had a helium core mass of about 50–55 M_⊙, corresponding to an initial mass of about 115 M_⊙.

Item Type:Article
Related URLs:
URLURL TypeDescription ReadCube access Paper
Lunnan, R.0000-0001-9454-4639
Leloudas, G.0000-0002-8597-0756
Perley, D. A.0000-0001-8472-1996
Quimby, R. M.0000-0001-9171-5236
Yan, Lin0000-0003-1710-9339
Blagorodnova, N.0000-0003-0901-1606
Bue, B. D.0000-0002-7856-3570
Cenko, S. B.0000-0003-1673-970X
De Cia, A.0000-0003-2082-1626
Cook, D. O.0000-0002-6877-7655
Gatkine, P.0000-0002-1955-2230
Gal-Yam, A.0000-0002-3653-5598
Kasliwal, M. M.0000-0002-5619-4938
Kulkarni, S. R.0000-0001-5390-8563
Masci, F. J.0000-0002-8532-9395
Nugent, P. E.0000-0002-3389-0586
Additional Information:© 2018 Springer Nature Limited. Received 07 March 2018; Accepted 02 August 2018; Published 10 September 2018. We are grateful for discussions with C.-I. Björnsson, S. Blinnikov, E. Sorokina, E. Ramirez-Ruiz and J. Fuller. The iPTF project is a scientific collaboration among the California Institute of Technology, Los Alamos National Laboratory, the University of Wisconsin, Milwaukee, the Oskar Klein Centre, the Weizmann Institute of Science, the TANGO Program of the University System of Taiwan, and the Kavli Institute for the Physics and Mathematics of the Universe. This work was supported by the GROWTH project funded by the National Science Foundation (NSF grant no. 1545949). This research was supported by the Swedish Research Council, the Swedish National Space Board, and the Knut and Alice Wallenberg Foundation. Part of this research was carried out at the Jet Propulsion Laboratory, California Institute of Technology, under a contract with the National Aeronautics and Space Administration (NASA). A.G.-Y. is supported by the European Union through ERC grant no. 725161, the Quantum Universe I-Core programme, the Israel Science Foundation, the BSF Transformative programme and a Kimmel award. P.E.N. acknowledges support from the US Department of Energy (DOE) through DE-FOA-0001088, Analytical Modeling for Extreme-Scale Computing Environments. This research used resources of the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the US DOE under contract no. DE-AC02-05CH11231. IRAF is distributed by the National Optical Astronomy Observatory, which is operated by the Association of Universities for Research in Astronomy under cooperative agreement with the NSF. Some of the data 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 financial support of the W.M. Keck Foundation. The authors wish to recognize and acknowledge the cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are fortunate to have the opportunity to conduct observations from this mountain. Author Contributions: R.L. coordinated the observational campaign, was PI of the Keck programme under which the late-time spectra were obtained, analysed the data and wrote the manuscript. C.F. wrote the resonance scattering code, ran the simulations, performed model comparisons, and contributed to manuscript writing. P.M.V. contributed to the interpretation and resonance line calculations and to the manuscript preparation. S.E.W. contributed to the comparison with PPI models and manuscript preparation. G.L., D.A.P., R.M.Q., L.Y., A.D.C. and A.G.-Y. contributed to the discovery, analysis, interpretation and manuscript preparation. M.M.K. contributed to manuscript preparation. S.R.K. is the PI of iPTF and of the P200/Keck programmes under which the early spectra were taken, and contributed to manuscript preparation. A.N. contributed to finding the supernova and to manuscript preparation. N.B., D.O.C. and A.R. reduced spectra. S.B.C. and P.G. obtained and reduced DCT photometry. C.U.F. reduced the P60 photometry. N.S. obtained and reduced the Subaru spectrum. F.J.M. and P.E.N. contributed to the photometric pipelines applied by iPTF. B.D.B. and P.W. contributed to the iPTF machine learning codes for transient search. The authors declare no competing interests. Code availability: The light echo modelling code is available from C.F. ( upon request. Data availability: The photometry of iPTF16eh is available in Supplementary Table 1, and the spectra are available from WISeREP35 ( In general, the data that support the plots within this paper and other findings of this study are available from the corresponding author upon reasonable request.
Group:Infrared Processing and Analysis Center (IPAC), Palomar Transient Factory
Funding AgencyGrant Number
Swedish Research CouncilUNSPECIFIED
Swedish National Space Board (SNSB)UNSPECIFIED
Knut and Alice Wallenberg FoundationUNSPECIFIED
European Research Council (ERC)725161
Quantum Universe I-Core ProgrammeUNSPECIFIED
Israel Science FoundationUNSPECIFIED
Binational Science Foundation (USA-Israel)UNSPECIFIED
Department of Energy (DOE)DE-FOA-0001088
Department of Energy (DOE)DE-AC02-05CH11231
W. M. Keck FoundationUNSPECIFIED
Subject Keywords:Stellar evolution; Time-domain astronomy; Transient astrophysical phenomena
Record Number:CaltechAUTHORS:20180910-104151114
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:89484
Deposited By: Tony Diaz
Deposited On:10 Sep 2018 18:08
Last Modified:21 May 2019 19:41

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