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 MV=−14.9 and exhibited an extended, flat plateau lasting ∼125 days. From the late-time bolometric light curve, we estimate a 56Ni mass of ∼0.01M⊙, 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 (≲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 Hα 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.
@article{arxiv.2601.02638,
title = {SN 2024abfl: A Flat-Plateau, Low-Luminosity Type IIP Supernova with Early CSM Interaction},
author = {Madison Gerard and Jennifer E. Andrews and Geoffrey C. Clayton and David J. Sand and K. Azalee Bostroem and Jeniveve Pearson and Raya Dastidar and Aravind P. Ravi and Conor L. Ransome and Bhagya Subrayan and Griffin Hosseinzadeh and Brian Hsu and Yize Dong and Manisha Shrestha and Stefano Valenti and Nathan Smith and Daryl Janzen and M. J. Lundquist and Nicolas Meza and Saurabh W. Jha and Kate D. Alexander and Collin Christy and Noah Franz and Lindsey A. Kwok and Moira Andrews and Joseph Farah and Daichi Hiramatsu and D. Andrew Howell and Curtis McCully and Kathryn Wynn and Reka Konyves-Toth and Xiaofeng Wang},
journal= {arXiv preprint arXiv:2601.02638},
year = {2026}
}