A1 Refereed original research article in a scientific journal
The bright long-lived Type II SN 2021irp powered by aspherical circumstellar material interaction: II. Estimating the CSM mass and geometry with polarimetry and light curve modeling
Authors: Reynolds, Thomas M.; Nagao, Takashi; Maeda, Keiichi; Elias-Rosa, Nancy; Fraser, Morgan; Gutierrez, Claudia; Kangas, Tuomas; Kuncarayakti, Hanindyo; Mattila, Seppo; Pessi, Priscila J.
Publisher: EDP Sciences
Publication year: 2025
Journal: Astronomy and Astrophysics
Article number: A213
Volume: 702
ISSN: 0004-6361
eISSN: 1432-0746
DOI: https://doi.org/10.1051/0004-6361/202553793
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/10.1051/0004-6361/202553793
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/505464580
Context
There is evidence of interaction between supernova (SN) ejecta and massive circumstellar material (CSM) among various types of SNe. The mass-ejection mechanisms that produce a massive CSM are unclear. Therefore, studying interacting SNe and their CSM can shed light on these mechanisms and the final stages of stellar evolution.
Aims
We aim to study the properties of the CSM in the bright, long-lived, hydrogen-rich (Type II) SN 2021irp, which is interacting with a massive aspherical CSM.
Methods
We present imaging and spectro-polarimetric observations of SN 2021irp. Modelling its polarisation and bolometric light curve allowed us to derive the CMS mass and distribution.
Results
SN 2021irp shows a high intrinsic polarisation of ∼0.8%. This high continuum polarisation suggests an aspherical photosphere created by an aspherical CSM interaction. Based on the bolometric light curve evolution and the high polarisation, SN 2021irp can be understood as a typical Type II SN interacting with a CSM disc with a corresponding mass-loss rate and half-opening angle of ∼0.035–0.1 M⊙ yr−1 and ∼30–50°, respectively. The total CSM mass we derived is ≳2 M⊙. We suggest that this CSM disc was created by some process related to binary interaction and that SN 2021irp is the end product of a typical massive star (i.e. with a ZAMS mass of ∼8 − 18 M⊙) that has a separation and/or mass ratio with its companion star which has led to an extreme mass ejection within decades of explosion. We propose that the particular spectroscopic properties of SN 2021irp and similar SNe can be explained through a a Type II SNe interacting with a massive disc CSM.
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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. and S. Mattila acknowledge support from the Research Council of Finland project 350458.
TN and HK acknowledge support from the Research Council of Finland projects 324504, 328898, and 353019. TK 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 program 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. 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). 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.
