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Two stripped envelope supernovae with circumstellar interaction. But only one really shows it

Sollerman, J. and Fransson, C. and Barbarino, C. and Fremling, C. and Horesh, A. and Kool, E. and Schulze, S. and Sfaradi, I. and Yang, S. and Bellm, E. C. and Burruss, R. and Cunningham, V. and De, K. and Drake, A. J. and Golkhou, V. Z. and Green, D. A. and Kasliwal, M. and Kulkarni, S. and Kupfer, T. and Laher, R. R. and Masci, F. J. and Rodriguez, H. and Rusholme, B. and Williams, D. R. A. and Yan, L. and Zolkower, J. (2020) Two stripped envelope supernovae with circumstellar interaction. But only one really shows it. Astronomy and Astrophysics, 643 . Art. No. A79. ISSN 0004-6361.

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Context. We present observations of SN 2019tsf (ZTF19ackjszs) and SN 2019oys (ZTF19abucwzt). These two stripped envelope (SE) Type Ib supernovae (SNe) suddenly showed a (re-)brightening in their late light curves. We investigate this in the context of circumstellar material (CSM) interaction with previously ejected material, a phenomenon that is unusual among SE SNe. Aims. We use our follow-up photometry and spectroscopy for these supernovae to demonstrate the presence of CSM interaction, estimate the properties of the CSM, and discuss why the signals are so different for the two objects. Methods. We present and analyze observational data, consisting of optical light curves and spectra. For SN 2019oys, we also have detections in radio as well as limits from UV and X-rays. Results. Both light curves show spectacular re-brightening after about 100 days. In the case of SN 2019tsf, the re-brightening is followed by a new period of decline, and the spectra never show signs of narrow emission lines that would indicate CSM interaction. On the contrary, SN 2019oys made a spectral makeover from a Type Ib to a spectrum clearly dominated by CSM interaction at the light curve brightening phase. Deep Keck spectra reveal a plethora of narrow high-ionization lines, including coronal lines, and the radio observations show strong emission. Conclusions. The rather similar light curve behavior – with a late linear re-brightening – of these two Type Ib SE SNe indicate CSM interaction as the powering source. For SN 2019oys the evidence for a phase where the ejecta hit H-rich material, likely ejected from the progenitor star, is conspicuous. We observe strong narrow lines of H and He, but also a plethora of high-ionization lines, including coronal lines, revealing shock interaction. Spectral simulations of SN 2019oys show two distinct density components, one with density ≳10⁹ cm⁻³, dominated by somewhat broader, low-ionization lines of H I, He I, Na I, and Ca II, and one with narrow, high-ionization lines at a density ∼10⁶ cm⁻³. The former is strongly affected by electron scattering, while the latter is unaffected. The evidence for CSM interaction in SN 2019oys is corroborated by detections in radio. On the contrary, for SN 2019tsf, we find little evidence in the spectra for any CSM interaction.

Item Type:Article
Related URLs:
URLURL TypeDescription Paper
Sollerman, J.0000-0003-1546-6615
Fransson, C.0000-0001-8532-3594
Barbarino, C.0000-0002-3821-6144
Fremling, C.0000-0002-4223-103X
Horesh, A.0000-0002-5936-1156
Kool, E.0000-0002-7252-3877
Schulze, S.0000-0001-6797-1889
Bellm, E. C.0000-0001-8018-5348
Cunningham, V.0000-0003-2292-0441
De, K.0000-0002-8989-0542
Golkhou, V. Z.0000-0001-8205-2506
Green, D. A.0000-0003-3189-9998
Kasliwal, M.0000-0002-5619-4938
Kulkarni, S.0000-0001-5390-8563
Kupfer, T.0000-0002-6540-1484
Laher, R. R.0000-0003-2451-5482
Masci, F. J.0000-0002-8532-9395
Rusholme, B.0000-0001-7648-4142
Williams, D. R. A.0000-0001-7361-0246
Yan, L.0000-0003-1710-9339
Additional Information:© 2020 ESO. Article published by EDP Sciences. Received 16 July 2020; Accepted 15 September 2020; Published online 06 November 2020. We thank Brad Cenko for guidance on the Swift data. David Titterington helped with AMI data and made corrections to the manuscript. Based on observations obtained with the Samuel Oschin Telescope 48-inch and the 60-inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under Grant No. AST-1440341 and a collaboration including Caltech, IPAC, the Weizmann Institute for Science, the Oskar Klein Center at Stockholm University, the University of Maryland, the University of Washington, Deutsches Elektronen- Synchrotron and Humboldt University, Los Alamos National Laboratories, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, and Lawrence Berkeley National Laboratories. Operations are conducted by COO, IPAC, and UW. This work was supported by the GROWTH project (Kasliwal et al. 2019) funded by the National Science Foundation under PIRE Grant No 1545949. The Oskar Klein Centre was funded by the Swedish Research Council. Gravitational Radiation and Electromagnetic Astrophysical Transients (GREAT) is funded by the Swedish Research council (VR) under Dnr 2016-06012. CF is supported by the Swedish Research Council and Swedish National Space Board. Partially based on observations made with the Nordic Optical Telescope, operated by the Nordic Optical Telescope Scientific Association at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias. Some of the data presented here were obtained with ALFOSC. 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. This paper is partly based on observations made with the Italian Telescopio Nazionale Galileo (TNG) operated on the island of La Palma by the Fundación Galileo Galilei of the INAF (Istituto Nazionale di Astrofisica) at the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias. The SED Machine is based upon work supported by the National Science Foundation under Grant No. 1106171. We thank the staff of the Mullard Radio Astronomy Observatory, University of Cambridge, for their support in the maintenance, and operation of AMI. We acknowledge support from the European Research Council under grant ERC-2012-StG-307215 LODESTONE. A.H. is grateful for the support by grants from the Israel Science Foundation, the US-Israel Binational Science Foundation, and the I-CORE Program of the Planning and Budgeting Committee and the Israel Science Foundation. We thank the referee for suggestions for how to improve Figs. 4 and 5.
Group:Astronomy Department, Infrared Processing and Analysis Center (IPAC), Zwicky Transient Facility
Funding AgencyGrant Number
ZTF partner institutionsUNSPECIFIED
Swedish Research Council2016-06012
Swedish National Space Board (SNSB)UNSPECIFIED
W. M. Keck FoundationUNSPECIFIED
European Research Council (ERC)307215
Israel Science FoundationUNSPECIFIED
Binational Science Foundation (USA-Israel)UNSPECIFIED
I-CORE Program of the Planning and Budgeting CommitteeUNSPECIFIED
Subject Keywords:supernovae: general
Record Number:CaltechAUTHORS:20200916-112949523
Persistent URL:
Official Citation:Two stripped envelope supernovae with circumstellar interaction - But only one really shows it. J. Sollerman, C. Fransson, C. Barbarino, C. Fremling, A. Horesh, E. Kool, S. Schulze, I. Sfaradi, S. Yang, E. C. Bellm, R. Burruss, V. Cunningham, K. De, A. J. Drake, V. Z. Golkhou, D. A. Green, M. Kasliwal, S. Kulkarni, T. Kupfer, R. R. Laher, F. J. Masci, H. Rodriguez, B. Rusholme, D. R. A. Williams, L. Yan and J. Zolkower. A&A, 643 (2020) A79; DOI:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:105428
Deposited By: George Porter
Deposited On:16 Sep 2020 21:42
Last Modified:06 Nov 2020 19:31

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