Early interaction signatures and an extended plateau phase in Type II SN 2020aze

Abstract We present a photometric and spectroscopic analysis of the fast-declining Type II SN 2020aze, observed in optical bands from 2.2 to 137.4 days post-explosion. The V-band light curve reaches a peak absolute magnitude of −16.97 ±0.20 mag by 15 days, followed by a recombination phase with a decline rate of 2.04 ± 0.13 mag (100 day)−1, lasting ~120 days. Early spectra (<6.0 day) exhibits a transient weak narrow emission line at 4687 Å and a bump or ledge feature spanning 4400-4800 Å, attributed to narrow and broad blue-shifted He ii λ4686, indicating interaction between the rapidly expanding ejecta and dense circumstellar material (CSM). Spectral comparison with literature models suggests a red supergiant progenitor with a weak wind and a mass-loss rate of ~10−3 M⊙ yr−1. Semi-analytical light curve modelling yields an initial radius of 1100 R⊙, an ejecta mass of 12 M⊙, a total explosion energy of 1.5× 1051 erg, and a progenitor mass of approximately 14 M⊙. The combination of a steep luminosity decline, early interaction signatures, and an unusually extended photospheric phase highlights the complex interplay between pre-SN mass loss, CSM interaction, and progenitor properties, positioning SN 2020aze as an important case for understanding the diversity of Type II SNe.

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Publication Details

Journal
Monthly Notices of the Royal Astronomical Society
Published
2026-05-12
DOI
https://doi.org/10.1093/mnras/stag875
Primary Topic
Gamma-ray bursts and supernovae
Type
article
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article

Early interaction signatures and an extended plateau phase in Type II SN 2020aze

C Pellegrino, V Kouprianov, T W Chen, B Ailawadhi et al.
Monthly Notices of the Royal Astronomical Society
Gamma-ray bursts and supernovae
article

Early interaction signatures and an extended plateau phase in Type II SN 2020aze

C Pellegrino, V Kouprianov, T W Chen, B Ailawadhi, P J Brown, S Valenti, D A Howell, J E Andrews, D Hiramatsu, N Dukiya, R Dastidar, J P Anderson, C McCully, K A Bostroem, S W Jha, L Yadav, M Gromadzki, C Inserra, G Pignata, R Cartier, D E Reichart, J Haislip, T E Müller-Bravo, E Padilla Gonzalez, D J Sand, D R Young, Jesper Sollerman, K Misra, Y Dong, D Janzen
article en

Abstract

Abstract We present a photometric and spectroscopic analysis of the fast-declining Type II SN 2020aze, observed in optical bands from 2.2 to 137.4 days post-explosion. The V-band light curve reaches a peak absolute magnitude of −16.97 ±0.20 mag by 15 days, followed by a recombination phase with a decline rate of 2.04 ± 0.13 mag (100 day)−1, lasting ~120 days. Early spectra (<6.0 day) exhibits a transient weak narrow emission line at 4687 Å and a bump or ledge feature spanning 4400-4800 Å, attributed to narrow and broad blue-shifted He ii λ4686, indicating interaction between the rapidly expanding ejecta and dense circumstellar material (CSM). Spectral comparison with literature models suggests a red supergiant progenitor with a weak wind and a mass-loss rate of ~10−3 M⊙ yr−1. Semi-analytical light curve modelling yields an initial radius of 1100 R⊙, an ejecta mass of 12 M⊙, a total explosion energy of 1.5× 1051 erg, and a progenitor mass of approximately 14 M⊙. The combination of a steep luminosity decline, early interaction signatures, and an unusually extended photospheric phase highlights the complex interplay between pre-SN mass loss, CSM interaction, and progenitor properties, positioning SN 2020aze as an important case for understanding the diversity of Type II SNe.

Monthly Notices of the Royal Astronomical Society
Rutgers, The State University of New Jersey (US), University of North Carolina at Chapel Hill (US), Physical Research Laboratory (IN), Queen's University Belfast (GB), Las Cumbres Observatory Global Telescope Network (US), Space Telescope Science Institute (US), Universidad de Antofagasta (CL), Goddard Space Flight Center (US), University of Arizona (US), M.J.P. Rohilkhand University (IN), University of California, Santa Barbara (US), University of Tarapacá (CL), Trinity College Dublin (IE), National Central University (TW), Mitchell Institute (US), Brera Astronomical Observatory (IT), Aryabhatta Research Institute of Observational Sciences (IN), University of Saskatchewan (CA), Gemini North Observatory (US), Environmental and Occupational Health Sciences Institute (US), Université Bourgogne Franche-Comté (FR), Institute of Astronomy (RU), Center for Astrophysics Harvard & Smithsonian (US), European Southern Observatory (CL), AlbaNova (SE), Astronomical Observatory (RS), The NSF AI Institute for Artificial Intelligence and Fundamental Interactions (US), University of Warsaw (PL), Cardiff University (GB), University of California, Davis (US), National Institute for Astrophysics (IT), Deen Dayal Upadhyaya Gorakhpur University (IN), Arturo Prat University (CL)
Openalex Percentile: Top 5%
Gamma-ray bursts and supernovae
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