ATLAS is primarily funded through NASA grants NN12AR55G, 80NSSC18K0284, and 80NSSC18K1575. The ATLAS science products are provided by the University of Hawaii, Queen's University Belfast, STScI, SAAO, and Millennium Institute of Astrophysics in Chile. M.N., S.S., A.A., and X.S. are supported by the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation program (grant agreement No. 948381) and by UK Space Agency grant No. ST/Y000692/1. Lasair is supported by the UKRI Science and Technology Facilities Council and is a collaboration between the University of Edinburgh (grant ST/N002512/1) and QUB (grant ST/N002520/1) within the LSST:UK Science Consortium. ZTF is supported by National Science Foundation grant 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. This work is based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere, Chile, as part of ePESSTO+ (the advanced Public ESO Spectroscopic Survey for Transient Objects Survey). ePESSTO+ observations were obtained under ESO program ID 108.220C (PI: Inserra). The Las Cumbres Observatory (LCO) data have been obtained via an OPTCON proposal (IDs: OPTICON 22A/004, 22B/002; European Union's Horizon 2020 grant agreement No. 730890), and the LCO team is supported by NSF grants AST-1911225 and AST-1911151. S.S., S.A.S., and S.J.S. acknowledge funding from STFC grants ST/X006506/1 and ST/T000198/1. D.B.J. and S.D.T.G. acknowledge funding from STFC grant awards ST/T00021X/1 and ST/X000923/1. D.B.J. and W.B. acknowledge support from the Leverhulme Trust via the Research Project Grant RPG-2019-371. L.G. and C.P.G. acknowledge financial support from the Spanish Ministerio de Ciencia e Innovación (MCIN), the Agencia Estatal de Investigación (AEI) 10.13039/501100011033, and the European Social Fund (ESF) "Investing in your future" under the 2019 Ramón y Cajal program RYC2019-027683-I; the Marie Skłodowska-Curie and the Beatriu de Pinós 2021 BP 00168 program and the PID2020-115253GA-I00 HOSTFLOWS project, from Centro Superior de Investigaciones Científicas (CSIC) under the PIE project 20215AT016; and the program Unidad de Excelencia María de Maeztu CEX2020-001058-M. We acknowledge funding from ANID, Millennium Science Initiative, ICN12_009. G.L. is supported by a research grant (19054) from VILLUM FONDEN. T.W.C. thanks the Yushan Young Fellow Program by the Ministry of Education, Taiwan for the financial support.

We present multiwavelength photometry and spectroscopy of SN 2022jli, an unprecedented Type Ic supernova discovered in the galaxy NGC 157 at a distance of ≈ 23 Mpc. The multiband light curves reveal many remarkable characteristics. Peaking at a magnitude of g = 15.11 ± 0.02, the high-cadence photometry reveals periodic undulations of 12.5 ± 0.2 days superimposed on the 200-day supernova decline. This periodicity is observed in the light curves from nine separate filter and instrument configurations with peak-to-peak amplitudes of ≃ 0.1 mag. This is the first time that repeated periodic oscillations, over many cycles, have been detected in a supernova light curve. SN 2022jli also displays an extreme early excess that fades over ≈25 days, followed by a rise to a peak luminosity of Lopt = 1042.1 erg s−1. Although the exact explosion epoch is not constrained by data, the time from explosion to maximum light is ≳ 59 days. The luminosity can be explained by a large ejecta mass (Mej ≈ 12 ± 6 M⊙) powered by 56Ni, but we find it difficult to quantitatively model the early excess with circumstellar interaction and cooling. Collision between the supernova ejecta and a binary companion is a possible source of this emission. We discuss the origin of the periodic variability in the light curve, including interaction of the SN ejecta with nested shells of circumstellar matter and neutron stars colliding with binary companions.

With funding from the Spanish government through the "Severo Ochoa Centre of Excellence" accreditation (CEX2020-001058-M).

Peer reviewed

Moore et al.