A1 Refereed original research article in a scientific journal
The bright long-lived Type II SN 2021irp powered by aspherical circumstellar material interaction I. Revealing the energy source with photometry and spectroscopy
Authors: Reynolds, Thomas M.; Nagao, Takashi; Gottumukkala, Rashmi; Gutierrez, Claudia P.; Kangas, Tuomas; Kravtsov, Timo; Kuncarayakti, Hanindyo; Maeda, Keiichi; Elias-Rosa, Nancy; Fraser, Morgan; Kotak, Rubina; Mattila, Seppo; Pastorello, Andrea; Pessi, Priscila J.; Cai, Yongzhi; Fynbo, Johan Peter Uldall; Kawabata, Miho; Lundqvist, Peter; Matilainen, Katja; Moran, Shane; Reguitti, Andrea; Taguchi, Kenta; Yamanaka, Masamichi
Publisher: EDP Sciences
Publication year: 2025
Journal: Astronomy and Astrophysics
Article number: A212
Volume: 702
ISSN: 0004-6361
eISSN: 1432-0746
DOI: https://doi.org/10.1051/0004-6361/202553792
Publication's open availability at the time of reporting: Open Access
Publication channel's open availability : Open Access publication channel
Web address : https://doi.org/10.1051/0004-6361/202553792
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/505460615
Context
Some core-collapse supernovae (CCSNe) are too luminous and radiate too much total energy to be powered by the release of thermal energy from the ejecta and radioactive-decay energy from the synthesised 56Ni/56Co. A source of additional power is the interaction between the supernova (SN) ejecta and the massive circumstellar material (CSM). This is an important power source in Type IIn SNe, which show narrow spectral lines arising from the unshocked CSM, but not all interacting SNe show such narrow lines.
Aims
We present photometric and spectroscopic observations of the hydrogen-rich SN 2021irp, which is both luminous, with Mo < −19.4 mag, and long-lived, remaining brighter than Mo = −18 mag for ∼250 d. We show that an additional energy source is required to power such a SN, and we determine the nature of the source. We also investigate the properties of the pre-existing and newly formed dust associated with the SN.
Methods
Photometric observations show that the luminosity of the SN is an order of magnitude higher than typical Type II SNe and persists for much longer. We detect an infrared excess attributed to dust emission. Spectra show multi-component line profiles, an Fe II pseudo-continuum, and a lack of absorption lines, all typical features of Type IIn SNe. We detect a narrow (< 85 kms−1) P Cygni profile associated with the unshocked CSM. An asymmetry in emission line profiles indicates dust formation occurring from 250–300 d. Analysis of the SN blackbody radius evolution indicates asymmetry in the shape of the emitting region.
Results
We identify the main power source of SN 2021irp as extensive interaction with a massive CSM, and that this CSM is distributed asymmetrically around the progenitor star. The infrared excess is explained with emission from newly formed dust although there is also some evidence of an IR echo from pre-existing dust at early times.
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Funding information in the publication:
T.M.R is part of the Cosmic Dawn Center (DAWN), which is funded by the Danish National Research Foundation under grant DNRF140. T.M.R acknowledges financial support from the Finnish Academy of Science and Letters through the Finnish postdoc pool. T.M.R and S. Mattila acknowledge support from the Research Council of Finland project 350458.
T.N. and H.K. acknowledge support from the Research Council of Finland projects 324504, 328898, and 353019. S. Moran acknowledges support from the Magnus Ehrnrooth Foundation and the Vilho, Yrjö and Kalle Väisälä Foundation. R.K. acknowledges support from the Research Council of Finland (grant 340613). T.K. acknowledges support from the Research Council of Finland project 360274. C.P.G. acknowledges financial support from the Secretary of Universities and Research(Government of Catalonia) and by the Horizon 2020 Research and Innovation Programme of the European Union under the Marie Skłodowska-Curie and the Beatriu de Pinós 2021 BP 00168 programme, the support from the Spanish Ministerio de Ciencia e Innovación (MCIN) and the Agencia Estatal de Investigación (AEI) 10.13039/501100011033 under the PID2023-151307NB-I00 SNNEXT project, from Centro Superior de Investigaciones Científicas (CSIC) under the PIE project 20215AT016 and the programme Unidad de Excelencia María de Maeztu CEX2020-001058-M, and from the Departament de Recerca i Universitats de la Generalitat de Catalunya through the 2021-SGR-01270 grant. Y.-Z. Cai is supported by the National Natural Science Foundation of China (NSFC, Grant No. 12303054), the National Key Research and Development Programme of China (Grant No. 2024YFA1611603), the Yunnan Fundamental Research Projects (Grant No. 202401AU070063), and the International Centre of Supernovae, Yunnan Key Laboratory (No. 202302AN360001). K.M. acknowledges support from the Japan Society for the Promotion of Science (JSPS) KAKENHI grant JP24KK0070 and 24H01810. The work is partly supported by the JSPS Open Partnership Bilateral Joint Research Projects between Japan and Finland (K.M. and H.K.; JPJSBP120229923) A.R. acknowledges financial support from the GRAWITA Large Programme Grant (PI P. D’Avanzo) and the PRIN-INAF 2022 “Shedding light on the nature of gap transients: from the observations to the models”. M.F. is supported by a Royal Society – Science Foundation Ireland University Research Fellowship. N.E.R. acknowledges support from the PRIN-INAF 2022, ‘Shedding light on the nature of gap transients: from the observations to the models This work was partly supported by Grant-in-Aid for Scientific Research (C) 22K03676. We acknowledge ESA Gaia, DPAC and the Photometric Science Alerts Team (http://gsaweb.ast.cam.ac.uk/alerts). This publication makes use of data products from the Two Micron All Sky Survey, which is a joint project of the University of Massachusetts and the Infrared Processing and Analysis Center/California Institute of Technology, funded by the National Aeronautics and Space Administration and the National Science Foundation. The spectrum taken by the Seimei telescope was obtained under the KASTOR (Kanata And Seimei Transient Observation Regime) project, specifically under the following programme for the Seimei Telescope at the Okayama observatory (21B-O-0009). The Seimei telescope at the Okayama Observatory is jointly operated by Kyoto University and the National Astronomical Observatory of Japan (NAOJ), with assistance provided by the Optical and InfraredSynergetic Telescopes for Education and Research (OISTER) programme. The Pan-STARRS1 Surveys (PS1) and the PS1 public science archive have been made possible through contributions by the Institute for Astronomy, the University of Hawaii, the Pan-STARRS Project Office, the Max-Planck Society and its participating institutes, the Max Planck Institute for Astronomy, Heidelberg and the Max Planck Institute for Extraterrestrial Physics, Garching, The Johns Hopkins University, Durham University, the University of Edinburgh, the Queen’s University Belfast, the Harvard-Smithsonian Center for Astrophysics, the Las Cumbres Observatory Global Telescope Network Incorporated, the National Central University of Taiwan, the Space Telescope Science Institute, the National Aeronautics and Space Administration under Grant No. NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate, the National Science Foundation Grant No. AST-1238877, the University of Maryland, Eotvos Lorand University (ELTE), the Los Alamos National Laboratory, and the Gordon and Betty Moore Foundation. Funding for the Sloan Digital Sky Survey IV has been provided by the Alfred P. Sloan Foundation, the U.S. Department of Energy Office of Science, and the Participating Institutions. SDSS-IV acknowledges support and resources from the Center for High Performance Computing at the University of Utah.
This research has made use of the NASA/IPAC Infrared Science Archive, which is funded by the National Aeronautics and Space Administration and operated by the California Institute of Technology.
