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Late-time observations of the extraordinary Type II supernova iPTF14hls

Sollerman, J. and Taddia, F. and Arcavi, I. and Fremling, C. and Fransson, C. and Burke, J. and Cenko, S. B. and Andersen, O. and Andreoni, I. and Barbarino, C. and Blagorodova, N. and Brink, T. G. and Filippenko, A. V. and Gal-Yam, A. and Hiramatsu, D. and Hosseinzadeh, G. and Howell, D. A. and de Jaeger, T. and Lunnan, R. and McCully, C. and Perley, D. A. and Tartaglia, L. and Terreran, G. and Valenti, S. and Wang, X. (2019) Late-time observations of the extraordinary Type II supernova iPTF14hls. Astronomy and Astrophysics, 621 . Art. No. A30. ISSN 0004-6361.

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Aims. We study iPTF14hls, a luminous and extraordinary long-lived Type II supernova, which lately has attracted much attention and disparate interpretation. Methods. We have presented new optical photometry that extends the light curves up to more than three years past discovery. We also obtained optical spectroscopy over this period, and furthermore present additional space-based observations using Swift and HST. Results. After an almost constant luminosity for hundreds of days, the later light curve of iPTF14hls finally fades and then displays a dramatic drop after about 1000 d, but the supernova is still visible at the latest epochs presented. The spectra have finally turned nebular, and our very last optical spectrum likely displays signatures from the deep and dense interior of the explosion. A high-resolution HST image highlights the complex environment of the explosion in this low-luminosity galaxy. Conclusions. We provide a large number of additional late-time observations of iPTF14hls, which are (and will continue to be) used to assess the many different interpretations for this intriguing object. In particular, the very late (+1000 d) steep decline of the optical light curve is difficult to reconcile with the proposed central engine models. The lack of very strong X-ray emission, and the emergence of intermediate-width emission lines including [S II] that we propose originate from dense, processed material in the core of the supernova ejecta, are also key observational tests for both existing and future models.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Sollerman, J.0000-0003-1546-6615
Arcavi, I.0000-0001-7090-4898
Fremling, C.0000-0002-4223-103X
Cenko, S. B.0000-0003-1673-970X
Filippenko, A. V.0000-0003-3460-0103
Gal-Yam, A.0000-0002-3653-5598
Hosseinzadeh, G.0000-0002-0832-2974
Howell, D. A.0000-0003-4253-656X
Lunnan, R.0000-0001-9454-4639
McCully, C.0000-0001-5807-7893
Perley, D. A.0000-0001-8472-1996
Tartaglia, L.0000-0003-3433-1492
Additional Information:© 2019 ESO. Article published by EDP Sciences. Received 21 June 2018; Accepted 23 October 2018; Published online 03 January 2019. We gratefully acknowledge support from the Knut and Alice Wallenberg Foundation. Based on observations obtained with the Samuel Oschin 48-inch telescope and the 60-inch telescope at the Palomar Observatory as part of the intermediate Palomar Transient Factory (iPTF) project, a scientific collaboration among the California Institute of Technology, Los Alamos National Laboratory, the University of Wisconsin (Milwaukee), the Oskar Klein Center, 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. The Oskar Klein Centre is funded by the Swedish Research Council. This work is partly based on observations made with DOLoRes at TNG, and on observations made with the Nordic Optical Telescope, operated by NOTSA at IAC using ALFOSC, which is provided by the IAA. 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. Some of the Keck observations were partially supported by Northwestern University and the Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA). Support for I. Arcavi was provided by NASA through the Einstein Fellowship Program, grant PF6-170148. R.L. acknowledge GROWTH. Research funding to I. Andreoni is provided by the Australian Astronomical Observatory. A.V.F. has been supported by the Christopher R. Redlich Fund, the TABASGO Foundation, and the Miller Institute for Basic Research in Science (U.C. Berkeley) where he is a Miller Senior Fellow. His work was conducted in part at the Aspen Center for Physics, which is supported by US National Science Foundation grant PHY-1607611; he thanks the Center for its hospitality during the supermassive black holes workshop in June and July 2018. X. W. is supported by the National Natural Science Foundation of China (NSFC grants 11325313 and 11633002). Special thanks to A. Bostroem and W. Zheng for help with Keck observations.
Funding AgencyGrant Number
Knut and Alice Wallenberg FoundationUNSPECIFIED
Swedish Research CouncilUNSPECIFIED
W. M. Keck FoundationUNSPECIFIED
Northwestern UniversityUNSPECIFIED
NASA Einstein FellowshipPF6-170148
Australian Astronomical Observatory (AAO)UNSPECIFIED
Christopher R. Redlich FundUNSPECIFIED
Miller Institute for Basic Research in ScienceUNSPECIFIED
National Natural Science Foundation of China11325313
National Natural Science Foundation of China11633002
Subject Keywords:supernovae: general – supernovae: individual: iPTF14hls
Record Number:CaltechAUTHORS:20190117-095029584
Persistent URL:
Official Citation:Late-time observations of the extraordinary Type II supernova iPTF14hls. J. Sollerman, F. Taddia, I. Arcavi, C. Fremling, C. Fransson, J. Burke, S. B. Cenko, O. Andersen, I. Andreoni, C. Barbarino, N. Blagorodova, T. G. Brink, A. V. Filippenko, A. Gal-Yam, D. Hiramatsu, G. Hosseinzadeh, D. A. Howell, T. de Jaeger, R. Lunnan, C. McCully, D. A. Perley, L. Tartaglia, G. Terreran, S. Valenti and X. Wang A&A, 621 (2019) A30. DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:92341
Deposited By: Tony Diaz
Deposited On:22 Jan 2019 22:03
Last Modified:22 Jan 2019 22:03

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