A1 Vertaisarvioitu alkuperäisartikkeli tieteellisessä lehdessä
The hydrogen-free circumstellar interaction in the Type Ib supernova 2021efd: A clue to the mechanism of the helium-layer stripping
Tekijät: Pyykkinen, N.; Nagao, T.; Kuncarayakti, H.; Stritzinger, M. D.; Kangas, T.; Maeda, K.; Chen, P.; Sollerman, J.; Burns, C.; Bose, S.; Folatelli, G.; Ferrari, L.; Morrell, N.; Reguitti, A.; Salmaso, I.; Mattila, S.; Gal-Yam, A.; Fremling, C.; Anand, S.; Kasliwal, M. M.; Gutierrez, C. P.; Galbany, L.; Hoogendam, W.; Schulze, S.; Ashall, C.; Medler, K.; Pfeffer, C. M.; Lundqvist, P.; Rusholme, B.; Adler, J.
Kustantaja: EDP Sciences
Julkaisuvuosi: 2026
Lehti: Astronomy and Astrophysics
Artikkelin numero: A183
Vuosikerta: 706
ISSN: 0004-6361
eISSN: 1432-0746
DOI: https://doi.org/10.1051/0004-6361/202557292
Julkaisun avoimuus kirjaamishetkellä: Avoimesti saatavilla
Julkaisukanavan avoimuus : Kokonaan avoin julkaisukanava
Verkko-osoite: https://doi.org/10.1051/0004-6361/202557292
Rinnakkaistallenteen osoite: https://research.utu.fi/converis/portal/detail/Publication/515778466
Rinnakkaistallenteen lisenssi: CC BY
Rinnakkaistallennetun julkaisun versio: Kustantajan versio
Context
Stripped-envelope supernovae (SESNe), including Type IIb, Ib, and Ic supernovae (SNe), originate from the explosions of massive stars whose outer envelopes have been largely removed during their lifetimes. The main stripping mechanism for the hydrogen (H) envelope in the progenitors of SESNe is often considered to be interaction with a binary companion, but the stripping mechanism for the helium (He) layer is unclear.
Aims
We study the process of the He-layer stripping in the progenitors of SESNe. This is closely related to the origin of their diverse observational properties.
Methods
We conducted photometric and spectroscopic observations of the Type Ib SN 2021efd, which shows signs of interaction with H-free circumstellar material (CSM). At early phases, its photometric and spectroscopic properties resemble those of typical Type Ib SNe. Around 30 days after the r-band light curve (LC) peak until at least ∼770 days, the luminosity of the multiband LCs is higher than that of regular SESNe and has at least three distinct peaks. The LC evolution is similar to that of SN 2019tsf, whose previously unpublished spectrum at 400 days is also presented here. The nebular spectrum of SN 2021efd shows narrow emission lines (∼1000 km s−1) in various species, such as O I, Ca II, Mg II, He I, [O I], [Ca II], and [S II]. Based on the observations, we studied the properties of the ejecta and CSM of SN 2021efd.
Results
Our observations suggest that SN 2021efd is a Type Ib SN that interacts with the CSM with the following parameters: The estimated ejecta mass, explosion energy, and 56Ni mass are 2.2 M⊙, 9.1 × 1050 erg, and 0.14 M⊙, respectively, and the estimated CSM mass, composition, and distribution are at least a few times 0.1 M⊙, H free, and clumpy, respectively. Based on the estimated ejecta properties, we conclude that this event is a transitional SN whose progenitor was experiencing He-layer stripping at the epoch of the explosion and was on the way to becoming a carbon-oxygen star (as the progenitors of Type Ic SNe) from a He star (as the progenitors of Type Ib SNe). The estimated CSM properties suggest that the progenitor had some episodic mass ejections at a rate of ∼5 × 10−3 − 10−2 M⊙ yr−1 for the last decade and slightly lower before this final phase at least from ∼200 years before the explosion for the assumed CSM velocity of 100 km s−1. For the case of ∼1000 km s−1, the necessary mass-loss rate would be higher by a factor of ten, and the timescales would be shorter by a factor of ten.
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Julkaisussa olevat rahoitustiedot:
NP, TN, and HK acknowledge support via the Research Council of Finland (grant 340613). H.K. and T.N. were funded by the Research Council of Finland projects 324504, 328898, 353019, and 340613. M.D. Stritzinger and S. Bose are funded by the Independent Research Fund Denmark (IRFD, grant number 10.46540/2032-00022B) and by an Aarhus University Research Foundation Nova project (AUFF-E-2023-9-28). T.K. acknowledges support from the Research Council of Finland project 360274. Based on observations made with the Nordic Optical Telescope (NOT), 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. The NOT data were obtained under program ID P62-505. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programs 105.20DF.001 and 108.2282.001 (PI: Kuncarayakti). 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 asteroids through 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. Based on observations obtained with the Samuel Oschin Telescope 48-inch and the 60-inch Telescope at the Palomar Observatory as part of the Zwicky Transient Facility project. ZTF is supported by the National Science Foundation under Grant No. AST-2034437 and a collaboration including Caltech, IPAC, the Weizmann Institute of Science, the Oskar Klein Center at Stockholm University, the University of Maryland, Deutsches ElektronenSynchrotron and Humboldt University, the TANGO Consortium of Taiwan, the University of Wisconsin at Milwaukee, Trinity College Dublin, Lawrence Livermore National Laboratories, IN2P3, University of Warwick, Ruhr University Bochum, Cornell University, and Northwestern University. Operations are conducted by COO, IPAC, and UW. The ZTF forced-photometry service was funded under the Heising-Simons Foundation grant #12540303 (PI: Graham). The Gordon and Betty Moore Foundation, through both the Data-Driven Investigator Program and a dedicated grant, provided critical funding for SkyPortal. SED Machine is based upon work supported by the National Science Foundation under Grant No. 1106171 Zwicky Transient Facility access was supported by Northwestern University and the Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA). This research has made use of the Spanish Virtual Observatory (https://svo.cab.inta-csic.es) project funded by MCIN/AEI/10.13039/501100011033/ through grant PID2020- 112949GB-I00. IS is supported by the PRIN-INAF 2022 project “Shedding light on the nature of gap transients: from the observations to the models”. AR acknowledges financial support from the GRAWITA Large Program Grant (PI P. D’Avanzo) and from the PRIN-INAF 2022 “Shedding light on the nature of gap transients: from the observations to the models”. K.M. acknowledges support from the Japan Society for the Promotion of Science (JSPS) KAKENHI grant (JP24KK0070, JP24H01810). The work is partly supported by the JSPS Open Partnership Bilateral Joint Research Projects between Japan and Finland (K.M and H.K; JPJSBP120229923). S.M. acknowledges financial support from the Research Council of Finland project 350458. L.G. acknowledges financial support from AGAUR, CSIC, MCIN and AEI 10.13039/501100011033 under projects PID2023-151307NB-I00, PIE 20215AT016, CEX2020-001058- M, ILINK23001, COOPB2304, and 2021-SGR-01270. AGY’s research is supported by ISF, IMOS and BSF grants, as well as the André Deloro Institute for Space and Optics Research, the Center for Experimental Physics, a WIS-MIT Sagol grant, the Norman E Alexander Family M Foundation ULTRASAT Data Center Fund, and Yeda-Sela; AGY is the incumbent of The Arlyn Imberman Professorial Chair. This material is based upon work supported by the National Science Foundation Graduate Research Fellowship Program under Grant Nos. 1842402 and 2236415. Any opinions, findings, conclusions, or recommendations expressed in this material are those of the author(s) and do not necessarily reflect the views of the National Science Foundation. CPG 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, 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 Cientificas (CSIC) under the PIE project 20215AT016 and the program Unidad de Excelencia Maria de Maeztu CEX2020-001058-M, and from the Departament de Recerca i Universitats de la Generalitat de Catalunya through the 2021-SGR-01270 grant.
