SN 2024abfl: A Flat-Plateau, Low-Luminosity Type IIP Supernova with Early CSM Interaction

TL;DR

SN 2024abfl is a low-luminosity Type IIP supernova with an extended flat plateau, early CSM interaction, and low nickel mass, providing valuable insights into progenitor mass loss and explosion diversity.

Contribution

This study presents detailed photometric and spectroscopic observations of SN 2024abfl, highlighting early CSM interaction and its implications for low-luminosity supernovae.

Findings

Extended flat plateau lasting ~125 days.

Detection of early CSM interaction signatures.

Low $^{56}$Ni mass (~0.01 M$_\

Abstract

We present photometric and spectroscopic observations of SN 2024abfl, a low-luminosity Type IIP supernova (LLSN) discovered shortly after explosion. The transient reached a peak absolute magnitude of $M_V = -14.9$ and exhibited an extended, flat plateau lasting $\sim$125 days. From the late-time bolometric light curve, we estimate a $^{56}$Ni mass of $\sim0.01~M_\odot$, consistent with other LLSNe. Analytical shock-cooling models fail to reproduce the rapid early rise, indicating that circumstellar material (CSM) interaction contributed to the initial emission. The spectroscopic evolution is typical of LLSNe, with relatively narrow metal lines and low expansion velocities ($\lesssim 3000$ km s$^{-1}$) that decline slowly over time. We detect a broad ``ledge'' feature around 4600 \AA within three days of explosion, which we interpret as a blend of high-ionization shock-accelerated CSM lines. Multi-peaked H$\alpha$ profiles develop during the plateau phase, consistent with complex ejecta-CSM interactions. As one of the best-observed examples of LLSNe, SN 2024abfl exhibits a weak explosion and signatures of nearby CSM, offering new insights into progenitor properties, pre-explosion mass loss, and the diversity of LLSNe.