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Massive stars exploding in a He-rich circumstellar medium XII. SN 2024acyl: A fast, linearly declining Type Ibn supernova with early flash-ionisation features
Tekijät: Cai, Y. -Z.; Pastorello, A.; Maeda, K.; Zhao, J. -W.; Wang, Z. -Y.; Peng, Z. -H.; Reguitti, A.; Tartaglia, L.; Filippenko, A. V.; Pan, Y.; Valerin, G.; Kumar, B.; Wang, Z.; Fraser, M.; Anderson, J. P.; Benetti, S.; Bose, S.; Brink, T. G.; Cappellaro, E.; Chen, T. -W.; Chen, X. -L.; Elias-rosa, N.; Esamdin, A.; Gal-yam, A.; Gonzalez-banuelos, M.; Gromadzki, M.; Gutierrez, C. P.; Inserra, C.; Iskandar, A.; Kangas, T.; Kankare, E.; Kravtsov, T.; Kuncarayakti, H.; Li, L. -P.; Liu, C. -X.; Liu, X. -K.; Lundqvist, P.; Matilainen, K.; Mattila, S.; Moran, S.; Muller-bravo, T. E.; Nagao, T.; Petrushevska, T.; Pignata, G.; Salmaso, I.; Smartt, S. J.; Sollerman, J.; Srivastav, S.; Stritzinger, M. D.; Wang, L. -T.; Yan, S. -Y.; Yang, Y.; Yang, Y. -P.; Zheng, W.; Zou, X. -Z.; Chen, L. -Y.; Du, X. -L.; Fang, Q. -L.; Fiore, A.; Ragosta, F.; Zha, S.; Zhang, J. -J.; Liu, X. W.; Bai, J. M.; Wang, B.; Wang, X. F.
Kustantaja: EDP Sciences
Julkaisuvuosi: 2026
Lehti: Astronomy and Astrophysics
Artikkelin numero: A157
Vuosikerta: 707
ISSN: 0004-6361
eISSN: 1432-0746
DOI: https://doi.org/10.1051/0004-6361/202558014
Julkaisun avoimuus kirjaamishetkellä: Avoimesti saatavilla
Julkaisukanavan avoimuus : Kokonaan avoin julkaisukanava
Verkko-osoite: https://doi.org/10.1051/0004-6361/202558014
Rinnakkaistallenteen osoite: https://research.utu.fi/converis/portal/detail/Publication/523437368
Rinnakkaistallenteen lisenssi: CC BY
Rinnakkaistallennetun julkaisun versio: Kustantajan versio
We present a photometric and spectroscopic analyses of the Type Ibn supernova (SN) 2024acyl. It rises to an absolute magnitude peak of Mo = −17.58 ± 0.15 mag in 10.6 days, and displays a rapid linear post-peak light-curve decline in all bands (e.g. γ0 − 60(V) = 0.097 ± 0.002 mag day−1), similar to most SNe Ibn. The optical pseudobolometric light curve peaks at (3.5 ± 0.8)×1042 erg s−1, with a total radiated energy of (5.0 ± 0.4)×1048 erg. The spectra are dominated by a blue continuum at early stages, with narrow P-Cygni He I lines and flash-ionisation emission lines of C III, N III, and He II. The P-Cygni He I features gradually evolve and become emission-dominated in late-time spectra. The Hα line is detected throughout the entire spectral evolution, which indicates that the circumstellar material (CSM) is helium-rich with some residual amount of hydrogen. Our multi-band light-curve modelling yields estimates of the ejecta mass of Mej = 0.49+0.11−0.09 M⊙ with a kinetic energy of Ek = 0.06+0.01−0.01 × 1051 erg, and a 56Ni mass of MNi = 0.018 M⊙. The inferred CSM properties are characterised by a mass of MCSM = 0.51+0.05−0.04 M⊙, an inner radius of R0=17.8+3.6−3.0 AU, and a density of ρCSM = (8.3+2.7−1.2) × 10−12 g cn−3. The multi-epoch spectra are well reproduced by the CMFGEN/ he4p0 model, corresponding to a He-ZAMS mass of 4 M⊙ (H-ZAMS mass 18.11 M⊙, pre-SN mass 3.16 M⊙). These findings are consistent with a scenario of an SN powered by ejecta-CSM interaction originating from a low-mass helium star that evolved within an interacting binary system where the CSM with some residual hydrogen may originate from the mass-transfer process. We also discuss an extreme scenario involving the possible merger of a helium white dwarf. In addition, a channel of core-collapse explosion of a late-type Wolf-Rayet (WR) star with hydrogen, or a transitional star between an Of and a WR type (e.g. an Ofpe/WN9 star) with fallback accretion cannot be entirely ruled out.
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We are grateful to the anonymous referee for insightful comments and suggestions that improved the paper. We thank Luc Dessart for kindly providing the spectral models for this Type Ibn SN. This work is supported by the National Key Research and Development Program of China (grants 2024YFA1611603, 2021YFA1600404), the National Natural Science Foundation of China (grants 12303054, 12225304, 12288102, 12373038), the Yunnan Fundamental Research Projects (grants 202401AU070063, 202501AS070078), the Yunnan Revitalization Talent Support Program (Yunling Scholar Project and Innovation Team Project), the Yunnan Science and Technology Program (grants 202501AS070005, 202201BC070003), the International Centre of Supernovae, Yunnan Key Laboratory (grant 202302AN360001), the Natural Science Foundation of Xinjiang Uygur Autonomous Region (grant 2024D01D32), and the Tianshan Talent Training Program (grant 2023TSYCLJ0053). A.P., A.R., S.B., E.C., N.E.R., and G.V. acknowledge support from the PRIN-INAF 2022, “Shedding light on the nature of gap transients: from the observations to the models.” A.R. was also supported by the GRAWITA Large Program Grant (PI P. D’Avanzo). E.C. acknowledges support from MIUR, PRIN 2020 (METE, grant 2020KB33TP). K.M. was supported by Japan Society for the Promotion of Science (JSPS) KAKENHI grants JP24KK0070 and JP24H01810, and by JSPS bilateral program JPJSBP120229923. B.K. is supported by the “Special Project for High-End Foreign Experts,” Xingdian Funding from Yunnan Province. T.-W.C. acknowledges financial support from the Yushan Fellow Program by the Ministry of Education, Taiwan (MOE-111-YSFMS-0008-001-P1) and the National Science and Technology Council, Taiwan (NSTC grant 114-2112-M-008-021-MY3). N.E.R. acknowledges support from the Spanish Ministerio de Ciencia e Innovación (MCIN) and the Agencia Estatal de Investigación (AEI) 10.13039/501100011033 under the program Unidad de Excelencia María de Maeztu CEX2020-001058-M. 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. Both C.P.G. and M.G.B. were supported by 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, by the Centro Superior de Investigaciones Científicas (CSIC) under the PIE project 20215AT016 and the programme Unidad de Excelencia María de Maeztu CEX2020-001058-M, and by the Departament de Recerca i Universitats de la Generalitat de Catalunya through the 2021-SGR-01270 grant. T.K. acknowledges support from the Research Council of Finland project 360274. S. Mattila acknowledges financial support from the Research Council of Finland project 350458. S. Moran is funded by Leverhulme Trust grant RPG-2023-240. M.D. Stritzinger is funded by the Independent Research Fund Denmark (IRFD, grant number 10.46540/2032-00022B). T.E.M.B. is funded by Horizon Europe ERC grant no. 101125877. T.P. acknowledges financial support from the Slovenian Research Agency (grants I0-0033, P1-0031, J1-2460 and N1-0344). H.K. was funded by the Research Council of Finland projects 324504, 328898, and 353019. A.F. acknowledges funding by the European Union – NextGenerationEU RFF M4C2 1.1 PRIN 2022 project “2022RJLWHN URKA” and by INAF 2023 Theory Grant ObFu 1.05.23.06.06 “Understanding R-process & Kilonovae Aspects (URKA).” J.Z. is supported by the National Key R&D Program of China with No. 2021YFA1600404, the National Natural Science Foundation of China (12173082, 12333008), the Yunnan Fundamental Research Projects (grants 202401BC070007 and 202201AT070069), the Top-notch Young Talents Program of Yunnan Province, the Light of West China Program provided by the Chinese Academy of Sciences, and the International Centre of Supernovae, Yunnan Key Laboratory (grant 202302AN360001). X.F.W. is supported by the National Natural Science Foundation of China (grants 12288102, 12033003, and 11633002) and the Tencent Xplorer Prize. A.V.F.’s research group at U.C. Berkeley acknowledges financial assistance from the Christopher R. Redlich Fund, as well as donations from Gary and Cynthia Bengier, Clark and Sharon Winslow, Alan Eustace and Kathy Kwan, William Draper, Timothy and Melissa Draper, Briggs and Kathleen Wood, Sanford Robertson (W.Z. is a Bengier-Winslow-Eustace Specialist in Astronomy, T.G.B. is a Draper-Wood-Robertson Specialist in Astronomy), and numerous other donors. We acknowledge the support of the staffs of the various observatories at which data were obtained. The observations were in part carried out within the framework of Subaru-Gemini time exchange program (under the project S24B-041 / GN-2024B-Q-101: PI, K. Maeda) which is operated by the National Astronomical Observatory of Japan. We are honored and grateful for the opportunity of observing the Universe from Maunakea, which has the cultural, historical and natural significance in Hawaii. Funding for the LJT has been provided by the CAS and the People’s Government of Yunnan Province. The LJT is jointly operated and administrated by YNAO and the Center for Astronomical Mega-Science, CAS. Based in part on observations made with the Nordic Optical Telescope, owned in collaboration by the University of Turku and Aarhus University, and operated jointly by Aarhus University, the University of Turku, and the University of Oslo, representing Denmark, Finland, and Norway, the University of Iceland, and Stockholm University at the Observatorio del Roque de los Muchachos, La Palma, Spain, of the Instituto de Astrofisica de Canarias. Observations from the NOT were obtained through the NUTS2 collaboration which is supported in part by the Instrument Centre for Danish Astrophysics (IDA), and the Finnish Centre for Astronomy with ESO (FINCA) via Academy of Finland grant nr 306531. The data presented here were obtained in part with ALFOSC, which is provided by the Instituto de Astrofisica de Andalucia (IAA) under a joint agreement with the University of Copenhagen and NOTSA. The Liverpool Telescope is operated on the island of La Palma by Liverpool John Moores University in the Spanish Observatorio del Roque de los Muchachos of the Instituto de Astrofisica de Canarias with financial support from the UK Science and Technology Facilities Council. 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 Astrofísica de Canarias. This article is also based on observations made in the Observatorios de Canarias del IAC with the Telescopio Nazionale Galileo, operated on the island of La Palma by INAF at the Observatorio del Roque de los Muchachos under the program A50TAC_41 (PI: G. Valerin). Based in part on observations collected at Copernico and Schmidt telescopes (Asiago Mount Ekar, Italy) of the INAF – Osservatorio Astronomico di Padova. The Chinese Tsinghua–Nanshan Optical Telescope (TNOT) operated at Nanshan Station by Xinjiang Astronomical Observatory of the Chinese Academy of Sciences, located in Xinjiang, China. Based in part on observations collected with the 0.8 m TNOT equipped with an Andor camera at Nanshan Station of Xinjiang Astronomical Observatory. Mephisto is developed at and operated by the South-Western Institute for Astronomy Research of Yunnan University (SWIFAR-YNU), funded by the “Yunnan University Development Plan for World-Class University” and “Yunnan University Development Plan for World-Class Astronomy Discipline.” Based on the “Key Laboratory of Survey Science of Yunnan Province” with project No. 202449CE340002. Based in part 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 – PI: Inserra). ePESSTO+ observations were obtained under ESO program ID 112.25JQ. A major upgrade of the Kast spectrograph on the Shane 3 m telescope at Lick Observatory, led by Brad Holden, was made possible through generous gifts from the Heising-Simons Foundation, William and Marina Kast, and the University of California Observatories. Research at Lick Observatory is partially supported by a generous gift from Google. This work has made use of data from the Asteroid Terrestrial-impact Last Alert System (ATLAS) project. The Asteroid Terrestrial-impact Last Alert System (ATLAS) project is primarily funded to search for near-Earth objects (NEOs) through National Aeronautics and Space Administration (NASA) grants NN12AR55G, 80NSSC18K0284, and 80NSSC18K1575; byproducts of the NEO search include images and catalogs from the survey area. This work was partially funded by Kepler/K2 grant J1944/80NSSC19K0112 and HST GO-15889, and STFC grants ST/T000198/1 and ST/S006109/1. The ATLAS science products have been made possible through the contributions of the University of Hawaii Institute for Astronomy, the Queen’s University Belfast, the Space Telescope Science Institute, the South African Astronomical Observatory, and The Millennium Institute of Astrophysics (MAS), Chile. Pan-STARRS is a project of the Institute for Astronomy of the University of Hawaii, and is supported by the NASA SSO Near Earth Observation Program under grants 80NSSC18K0971, NNX14AM74G, NNX12AR65G, NNX13AQ47G, NNX08AR22G, 80NSSC21K1572 and by the State of Hawaii. 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, STScI, NASA under grant NNX08AR22G issued through the Planetary Science Division of the NASA Science Mission Directorate, NSF grant AST-1238877, the University of Maryland, Eotvos Lorand University (ELTE), the Los Alamos National Laboratory, and the Gordon and Betty Moore Foundation. We acknowledge the use of public data from the Swift data archive. SDSS is managed by the Astrophysical Research Consortium for the Participating Institutions of the SDSS Collaboration including the Brazilian Participation Group, the Carnegie Institution for Science, Carnegie Mellon University, Center for Astrophysics | Harvard & Smithsonian (CfA), the Chilean Participation Group, the French Participation Group, Instituto de Astrofísica de Canarias, The Johns Hopkins University, Kavli Institute for the Physics and Mathematics of the Universe (IPMU) / University of Tokyo, the Korean Participation Group, Lawrence Berkeley National Laboratory, Leibniz Institut für Astrophysik Potsdam (AIP), Max-Planck-Institut für Astronomie (MPIA Heidelberg), Max-Planck-Institut für Astrophysik (MPA Garching), Max-Planck-Institut für Extraterrestrische Physik (MPE), National Astronomical Observatories of China, New Mexico State University, New York University, University of Notre Dame, Observatório Nacional / MCTI, The Ohio State University, Pennsylvania State University, Shanghai Astronomical Observatory, United Kingdom Participation Group, Universidad Nacional Autónoma de México, University of Arizona, University of Colorado Boulder, University of Oxford, University of Portsmouth, University of Utah, University of Virginia, University of Washington, University of Wisconsin, Vanderbilt University, and Yale University. This research has made use of the NASA/IPAC Extragalactic Database (NED), which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with NASA.
