SN 2021ukt: A Transitional Supernova with a Short Plateau and Persistent Interaction
Neil R. Pichay, Sergiy S. Vasylyev, Audrey M. Liddle, Alexei V. Filippenko, WeiKang Zheng, Thomas G. Brink, Yi Yang, Matthew Graham, Daniel Stern, Daichi Hiramatsu, Claudia P. Guti\'errez, K. Azalee Bostroem, Estefania Padilla Gonzalez, D. Andrew Howell, Curtis McCully

TL;DR
SN 2021ukt is a transitional supernova exhibiting a short 25-day plateau, persistent ejecta-CSM interaction, and a progenitor with a ZAMS mass around 12 solar masses, highlighting a continuum of supernova progenitor evolution.
Contribution
This work documents a rare supernova transition from Type IIn to Type Ib, providing detailed spectroscopic, photometric, and modeling analysis of its unique features.
Findings
Short plateau indicates a thin hydrogen-rich envelope.
Persistent Hα emission suggests ongoing ejecta-CSM interaction.
Progenitor estimated to have ~12 solar masses ZAMS mass.
Abstract
We present spectroscopic and photometric observations of supernova (SN) 2021ukt, a peculiar short-plateau object that was originally identified as a Type IIn SN and later underwent an unprecedented transition to a Type Ib (possibly Type IIb) SN. The early-time light curves of SN 2021ukt exhibit a ~25 day plateau. Such a short phase of hydrogen recombination suggests a rather thin H-rich outer envelope of the progenitor star. The relatively narrow Balmer emission lines in spectra of SN 2021ukt during the first week indicate the interaction between the expanding ejecta and the immediate circumstellar material (CSM). This H{\alpha} line is observed throughout its helium-rich ejecta-dominated phase and nebular phase, suggesting persistent interaction with a radially extended CSM profile. We explore the synthetic light-curve model among grids of parameters generated by MESA+STELLA. We also…
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Taxonomy
TopicsGamma-ray bursts and supernovae · Viral gastroenteritis research and epidemiology · Neutrino Physics Research
