SN 2023axu: A Type IIP Supernova Interacted with a Low-Density Stellar Wind

TL;DR

SN 2023axu, a Type IIP supernova, shows typical light curves but exhibits a unique spectral feature indicating weak interaction with a low-density stellar wind, providing insights into progenitor mass-loss history.

Contribution

This study presents detailed photometric and spectroscopic observations of SN 2023axu, revealing a distinctive spectral feature and evidence of weak ejecta-wind interaction, expanding understanding of SNe II progenitor environments.

Findings

Light curve consistent with normal SNe IIP

Spectral feature attributed to C, N, He blend from weak ejecta-wind interaction

Progenitor mass estimated at ~15 solar masses

Abstract

We present photometric and spectroscopic observations of Type IIP supernova SN 2023axu, spanning $\sim$400 d after the explosion. Its light curve is typical of normal SNe IIP, with a V-band peak of $-17.25 \pm 0.06$ mag and no early-time excess indicative of strong circumstellar interaction. The early spectra exhibit a distinctive broad "ledge" near 4600 \AA. Through spectral modeling and comparison, we attribute this feature to a blend of C, N, and He lines excited by weak interaction between the ejecta and a low-density stellar wind. The late-time photometric evolution shows no discernible contribution from interaction, arguing against strong late-time circumstellar material engagement and supporting the low-density wind scenario. From modeling, this SN synthesized $\sim 0.055\,M_\odot$ of $^{56}$Ni, and nebular spectrum analysis indicates a progenitor mass near $15\,M_\odot$. SN 2023axu thus exemplifies weak ejecta-wind interaction and highlights the diversity of mass-loss histories and circumstellar environments of SNe II progenitors.