[Paper Review] SN 2024abfl: A Low-Luminosity Type IIP Supernova in NGC 2146 from a Low-Mass Red Supergiant Progenitor

Xiaohan Chen, Ning-Chen Sun+45 more|arXiv (Cornell University)|Feb 4, 2026

Gamma-ray bursts and supernovae0 citations

TL;DR

The paper presents photometric and spectroscopic analysis of SN 2024abfl, a low-luminosity Type IIP supernova in NGC 2146 with a directly detected low-mass red supergiant progenitor, deriving a low Ni mass, ejecta mass, and explosion energy.

ABSTRACT

Type IIP supernovae (SNe IIP) exhibit a significant diversity in their explosion properties, yet the physical mechanisms driving this diversity remain unknown. In this work, we present photometric and spectroscopic observations of SN 2024abfl, a SN IIP in NGC 2146 with a directly detected red supergiant (RSG) progenitor. We find it has a low plateau luminosity ($M_V \sim -15$ mag) and a relatively long plateau length ($\sim 126.5$ days). By fitting a semi-analytical model, we estimated a $^{56}$Ni mass of $\sim 0.009 M_\odot$, an initial kinetic energy of $\sim 0.42$ foe, an initial thermal energy of $\sim 0.03$ foe and an ejecta mass of $\sim 8.3 M_\odot$. The spectral evolution of SN 2024abfl is similar to those of other SNe IIP, except for much lower ejecta velocities at similar epochs. At later epochs, we find a relatively high-velocity H$α$ absorption feature at $\sim -4000$ km s$^{-1}$, possibly due to a fast-moving plume of matter in the inner ejecta, and two emission features at $\pm 2000$ km s$^{-1}$, possibly caused by CSM interaction. We estimate the progenitor mass to be $\le 15 M_\odot$ based on nebular spectra. We conclude that SN 2024abfl is a low-luminosity SN IIP originating from a low-mass RSG progenitor.

Motivation & Objective

• Investigate the explosion properties of a low-luminosity Type IIP supernova with a directly detected low-mass RSG progenitor.
• Characterize the light-curve features, including plateau length and luminosity, and compare with the broader SNe IIP population.
• Estimate the 56Ni mass, ejecta mass, kinetic and thermal energies to place SN 2024abfl within LL SNe IIP.
• Constrain the progenitor mass through nebular-phase spectral diagnostics and progenitor detections.
• Assess evidence for CSM interaction and its impact on the early and late-time evolution.

Proposed method

• Gather multi-band photometry (g, r, i, B, V, R, I, UVOT) and spectroscopy from XL-60/XL-35, TRT, LT, NOT, Gemini-N, HCT across ~4 to ~199 days.
• Construct bolometric luminosity, temperature, and radius using the SuperBol framework with Swift UVOT and optical data.
• Estimate 56Ni mass from the tail luminosity using the Hamuy (2003) relation and cross-check with radioactive decay modeling.
• Fit a semi-analytical light-curve model (Nag y et al. 2014; Jäger et al. 2020) with MCMC to derive R0, Mej, MNi, Ekin, Eth, matching the bolometric light curve.
• Analyze spectral evolution to measure ejecta velocities (Hα) and identify potential CSM interaction signatures.
• Use nebular-phase [O I]/[Ca II] flux ratios to constrain progenitor mass (≤15 Msun).

Experimental results

Research questions

• RQ1 What are the explosion parameters (Ni mass, ejecta mass, energies) of SN 2024abfl and how do they compare to normal SNe IIP and LL SNe IIP?
• RQ2 Is SN 2024abfl consistent with a low-mass red supergiant progenitor, and what is the constrained progenitor mass?
• RQ3 What nebular-phase spectral diagnostics reveal about the progenitor mass and envelope structure?
• RQ4 Are there signs of circumstellar interaction influencing early or late-time evolution?
• RQ5 How does SN 2024abfl fit into the broader LL SNe IIP population in terms of plateau length and luminosity?

Key findings

• SN 2024abfl has a low plateau luminosity with M_V ~ -15 mag and a long plateau of ~126.5 days.
• The tail modeling and bolometric analysis yield a 56Ni mass of ~0.009 Msun and an ejecta mass of ~8.3 Msun.
• The inferred initial kinetic energy is ~0.42 foe, with a small initial thermal energy ~0.03 foe.
• Nebular spectra imply a progenitor mass ≤15 Msun, consistent with direct progenitor detections of ~9–12 Msun.
• Spectral evolution shows low ejecta velocities (~2800–3800 km/s) during the plateau, with a late high-velocity Hα feature (~-4200 km/s) and ±2000 km/s emission features indicative of CSM interaction.
• Compared to normal SNe IIP, SN 2024abfl exhibits lower Ni mass, lower ejecta mass, and lower explosion energy, aligning with LL SNe IIP.
• Evidence from early-time spectra and CSM-related features suggests interaction with circumstellar material.