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Published May 11, 2015 | Published + Submitted
Journal Article Open

PTF11iqb: cool supergiant mass-loss that bridges the gap between Type IIn and normal supernovae

Abstract

The supernova (SN) PTF11iqb was initially classified as a Type IIn event caught very early after explosion. It showed narrow Wolf–Rayet (WR) spectral features on day 2 (as in SN 1998S and SN 2013cu), but the narrow emission weakened quickly and the spectrum morphed to resemble Types II-L and II-P. At late times, Hα exhibited a complex, multipeaked profile reminiscent of SN 1998S. In terms of spectroscopic evolution, we find that PTF11iqb was a near twin of SN 1998S, although with somewhat weaker interaction with circumstellar material (CSM) at early times, and stronger interaction at late times. We interpret the spectral changes as caused by early interaction with asymmetric CSM that is quickly (by day 20) enveloped by the expanding SN ejecta photosphere, but then revealed again after the end of the plateau when the photosphere recedes. The light curve can be matched with a simple model for CSM interaction (with a mass-loss rate of roughly 10^(−4) M_⊙ yr^(−1)) added to the light curve of a normal SN II-P. The underlying plateau requires a progenitor with an extended hydrogen envelope like a red supergiant at the moment of explosion, consistent with the slow wind speed (<80 km s^(−1)) inferred from narrow Hα emission. The cool supergiant progenitor is significant because PTF11iqb showed WR features in its early spectrum – meaning that the presence of such WR features does not necessarily indicate a WR-like progenitor. Overall, PTF11iqb bridges SNe IIn with weaker pre-SN mass-loss seen in SNe II-L and II-P, implying a continuum between these types.

Additional Information

© 2015 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2015 February 16. Received 2015 February 13; in original form 2015 January 8. First published online March 26, 2015. We thank Iair Arcavi, Peter Blanchard, Yi Cao, Ori Fox, Paul Groot, Asaf Horesh, Michael Kandrashoff, Pat Kelly, Nick Konidaris, Rubina Kotak, David Levitan, Adam Miller, Yen-Chen Pan, Jarod Parrent, Paul Smith, and Wei Kang Zheng for assistance with some of the observations and data reduction. We thank Eran Ofek for helpful discussions and assistance with the PTF photometric data. We thank the referee, Max Stritzinger, for a careful reading of the manuscript and helpful comments. We thank the staffs at Lick, MMT, LBT, Keck, Palomar, and WHT for their assistance with the observations. Observations using Steward Observatory facilities were obtained as part of the observing program AZTEC: Arizona Transient Exploration and Characterization. Some observations reported here were obtained at the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution. This research was based in part on observations made with the LBT. The LBT is an international collaboration among institutions in the United States, Italy and Germany. The LBT Corporation partners are: the University of Arizona on behalf of the Arizona university system; the Istituto Nazionale di Astrofisica, Italy; the LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, the Astrophysical Institute Potsdam and Heidelberg University; the Ohio State University and the Research Corporation, on behalf of the University of Notre Dame, University of Minnesota and University of Virginia. The WHT is operated on the island of La Palma by the Isaac Newton Group in the Spanish Observatorio del Roque de los Muchachos of the Instituto de AstrofÃsica de Canarias. 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. The authors wish to recognize and acknowledge the very significant cultural role and reverence that the summit of Mauna Kea has always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from this mountain. NS received partial support from NSF grants AST-1210599 and AST-1312221. E.O.O. is incumbent of the Arye Dissentshik career development chair and is grateful to support by grants from the Willner Family Leadership Institute Ilan Gluzman (Secaucus NJ), Israeli Ministry of Science, Israel Science Foundation, Minerva and the I-CORE Program of the Planning and Budgeting Committee and The Israel Science Foundation. AGY is supported by the EU/FP7 via ERC grant no. 307260, the Quantum Universe I-Core program by the Israeli Committee for planning and funding, and the ISF, Minerva and ISF grants, WIS-UK 'making connections,' and Kimmel and ARCHES awards. The supernova research of AVF's group at U.C. Berkeley is supported by Gary & Cynthia Bengier, the Richard & Rhoda Goldman Fund, the Christopher R. Redlich Fund, the TABASGO Foundation, and NSF grant AST-1211916. JMS is supported by an NSF Astronomy and Astrophysics Postdoctoral Fellowship under award AST-1302771.KM is supported by a Marie Curie Intra-European Fellowship, within the 7th European Community Framework Programme (FP7). MS acknowledges support from the Royal Society. DCL and JCH are grateful for support from NSF grants AST-1009571 and AST-1210311, under which part of this research (photometry collected at MLO) was carried out.

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Published - MNRAS-2015-Smith-1876-96.pdf

Submitted - 1501.02820v1.pdf

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Additional details

Created:
August 20, 2023
Modified:
October 23, 2023