TY - JOUR
T1 - The electron-capture origin of supernova 2018zd
AU - Hiramatsu, Daichi
AU - Howell, D. Andrew
AU - Van Dyk, Schuyler D.
AU - Goldberg, Jared A.
AU - Maeda, Keiichi
AU - Moriya, Takashi J.
AU - Tominaga, Nozomu
AU - Nomoto, Ken’ichi
AU - Hosseinzadeh, Griffin
AU - Arcavi, Iair
AU - McCully, Curtis
AU - Burke, Jamison
AU - Bostroem, K. Azalee
AU - Valenti, Stefano
AU - Dong, Yize
AU - Brown, Peter J.
AU - Andrews, Jennifer E.
AU - Bilinski, Christopher
AU - Williams, G. Grant
AU - Smith, Paul S.
AU - Smith, Nathan
AU - Sand, David J.
AU - Anand, Gagandeep S.
AU - Xu, Chengyuan
AU - Filippenko, Alexei V.
AU - Bersten, Melina C.
AU - Folatelli, Gastón
AU - Kelly, Patrick L.
AU - Noguchi, Toshihide
AU - Itagaki, Koichi
N1 - Funding Information:
We are grateful to A. Suzuki, T. Takiwaki, T. Nozawa, M. Tanaka, C. Kobayashi, R. Ouchi, T. Matsuoka, T. Hayakawa, S. I. Blinnikov, K. Chen, L. Bildsten and B. Paxton for comments and discussions, to C. P. Gutiérrez and A. Pastorello for sharing the velocity data of the type II SN sample and SN 2005cs (respectively), and to P. Iláš for creating the colour-composite image. D.H., D.A.H., G.H., C.M. and J.B. were supported by the US National Science Foundation (NSF) grants AST-1313484 and AST-1911225, as well as by the National Aeronautics and Space Administration (NASA) grant 80NSSC19kf1639. D.H. is thankful for support and hospitality by the Kavli Institute for the Physics and Mathematics of the Universe (IPMU) where many discussions of this work took place. J.A.G. is supported by the NSF GRFP under grant 1650114. K.M. acknowledges support by JSPS KAKENHI grants 20H00174, 20H04737, 18H04585, 18H05223 and 17H02864. K.N.’s work and D.H.’s visit to Kavli IPMU have been supported by the World Premier International Research Center Initiative (WPI Initiative), MEXT, and JSPS KAKENHI grants JP17K05382 and JP20K04024, Japan. I.A. is a CIFAR Azrieli Global Scholar in the Gravity and the Extreme Universe Program and acknowledges support from that programme, from the Israel Science Foundation (grants 2108/18 and 2752/19), from the United States – Israel Binational Science Foundation (BSF), and from the Israeli Council for Higher Education Alon Fellowship. Research by K.A.B., S.V. and Y.D. is supported by NSF grant AST-1813176. J.E.A. and N.S. receive support from NSF grant AST-1515559. Research by D.J.S. is supported by NSF grants AST-1821967, 1821987, 1813708, 1813466 and 1908972. G.S.A. acknowledges support from the Infrared Processing and Analysis Center (IPAC) Visiting Graduate Student Fellowship and from NASA/HST grant SNAP-15922 from the Space Telescope Science Institute (STScI), which is operated by the Association of Universities for Research in Astronomy (AURA), Inc., under NASA contract NAS5-26555. A.V.F. is grateful for financial assistance from the Christopher R. Redlich Fund, the TABASGO Foundation, and the UC Berkeley Miller Institute for Basic Research in Science (where he is a Senior Miller Fellow); additional funding was provided by NASA/HST grant AR-14295 from STScI. G.F. acknowledges support from CONICET through grant PIP-2015-2017-11220150100746CO and from ANPCyT through grant PICT-2017-3133. This paper made use of data from the Las Cumbres Observatory global network of telescopes through the Global Supernova Project. Some of the observations reported herein were obtained at the Bok 2.3m telescope, a facility of the University of Arizona, at the MMT Observatory, a joint facility of the University of Arizona and the Smithsonian Institution, and 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 Keck Observatory was made possible by the generous financial support of the W. M. Keck Foundation. This work is partly based on observations made with the NASA/ESA Hubble Space Telescope, obtained from the Data Archive at STScI. These observations are associated with programmes GO-9788, GO-13007 and GO-15151. Financial support for programme GO-15151 was provided by NASA through a grant from STScI. This work is based in part on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under a contract with NASA. We thank the support of the staffs at the Neil Gehrels Swift Observatory. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is funded by NASA and operated by the California Institute of Technology, as well as IRAF, which is distributed by NOAO (operated by AURA, Inc.), under cooperative agreement with NSF. Numerical computations were in part carried out on the PC cluster at the Center for Computational Astrophysics, the National Astronomical Observatory of Japan. We recognize and acknowledge the very significant cultural role and reverence that the summits of Maunakea and Haleakala have always had within the indigenous Hawaiian community. We are most fortunate to have the opportunity to conduct observations from these mountains.
Publisher Copyright:
© 2021, The Author(s), under exclusive licence to Springer Nature Limited.
PY - 2021/9
Y1 - 2021/9
N2 - In the transitional mass range (~8–10 solar masses) between white dwarf formation and iron core-collapse supernovae, stars are expected to produce an electron-capture supernova. Theoretically, these progenitors are thought to be super-asymptotic giant branch stars with a degenerate O + Ne + Mg core, and electron capture onto Ne and Mg nuclei should initiate core collapse1–4. However, no supernovae have unequivocally been identified from an electron-capture origin, partly because of uncertainty in theoretical predictions. Here we present six indicators of electron-capture supernovae and show that supernova 2018zd is the only known supernova with strong evidence for or consistent with all six: progenitor identification, circumstellar material, chemical composition5–7, explosion energy, light curve and nucleosynthesis8–12. For supernova 2018zd, we infer a super-asymptotic giant branch progenitor based on the faint candidate in the pre-explosion images and the chemically enriched circumstellar material revealed by the early ultraviolet colours and flash spectroscopy. The light-curve morphology and nebular emission lines can be explained by the low explosion energy and neutron-rich nucleosynthesis produced in an electron-capture supernova. This identification provides insights into the complex stellar evolution, supernova physics, cosmic nucleosynthesis and remnant populations in the transitional mass range.
AB - In the transitional mass range (~8–10 solar masses) between white dwarf formation and iron core-collapse supernovae, stars are expected to produce an electron-capture supernova. Theoretically, these progenitors are thought to be super-asymptotic giant branch stars with a degenerate O + Ne + Mg core, and electron capture onto Ne and Mg nuclei should initiate core collapse1–4. However, no supernovae have unequivocally been identified from an electron-capture origin, partly because of uncertainty in theoretical predictions. Here we present six indicators of electron-capture supernovae and show that supernova 2018zd is the only known supernova with strong evidence for or consistent with all six: progenitor identification, circumstellar material, chemical composition5–7, explosion energy, light curve and nucleosynthesis8–12. For supernova 2018zd, we infer a super-asymptotic giant branch progenitor based on the faint candidate in the pre-explosion images and the chemically enriched circumstellar material revealed by the early ultraviolet colours and flash spectroscopy. The light-curve morphology and nebular emission lines can be explained by the low explosion energy and neutron-rich nucleosynthesis produced in an electron-capture supernova. This identification provides insights into the complex stellar evolution, supernova physics, cosmic nucleosynthesis and remnant populations in the transitional mass range.
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U2 - 10.1038/s41550-021-01384-2
DO - 10.1038/s41550-021-01384-2
M3 - Article
AN - SCOPUS:85115451852
SN - 2397-3366
VL - 5
SP - 903
EP - 910
JO - Nature Astronomy
JF - Nature Astronomy
IS - 9
ER -