Ailawadhi, B., Dastidar, R., Misra, K., Valenti, S., Sand, D. J. and Inserra, C.  ORCID: https://orcid.org/0000-0002-3968-4409
2026.
Early interaction signatures and an extended plateau phase in Type II SN 2020aze.
Monthly Notices of the Royal Astronomical Society
549
(2)
, stag875.
10.1093/mnras/stag875
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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.
| Item Type: | Article |
|---|---|
| Date Type: | Publication |
| Status: | Published |
| Schools: | Schools > Physics and Astronomy |
| Additional Information: | For full list of authors please see article webpage https://doi.org/10.1093/mnras/stag875 |
| Publisher: | Oxford University Press (OUP) |
| ISSN: | 0035-8711 |
| Date of First Compliant Deposit: | 18 May 2026 |
| Date of Acceptance: | 26 April 2026 |
| Last Modified: | 08 Jun 2026 13:06 |
| URI: | https://orca.cardiff.ac.uk/id/eprint/187032 |
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