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

TL;DR

SN 2024abfl is a low-luminosity Type IIP supernova in NGC 2146 with a directly detected red supergiant progenitor. Through multi-band photometry, time-series spectroscopy, and bolometric/semi-analytic modelling, the study derives a nickel mass of $M_{ ext{Ni}} \\approx 0.009\ M_\\odot$, an ejecta mass of $M_ ext{ej} \\approx 8.3\ M_\\odot$, and a kinetic energy of $E_ ext{kin} \\approx 0.42$ foe, consistent with LL SNe IIP. The plateau remains long ($\\sim126.5$ days) with a relatively faint peak ($M_V \\sim -15$ mag), and nebular-phase line ratios yield a progenitor mass $\\le 15\ M_\\odot$, aligning with the direct progenitor mass estimate of ~9–12 $M_\\odot$. Collectively, the results support the scenario that LL SNe IIP originate from low-mass red supergiants and highlight early CSM interaction as a potential contributor to the initial light-curve peak.

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.

Figures (9)

• Figure 1: SN 2024abfl and its host galaxy NGC 2146. Shown is an RGB composite assembled from Xinglong 35-cm telescope g-, r-, and i-band exposures at t = 4.4 days after the explosion.
• Figure 2: Normalized Gemini spectrum of SN 2024abfl at t = 3.2 day, showing prominent Na I D absorption features. The observed data (black points) are fitted with Gaussian profiles (red curves). The left absorption component arises from the Milky Way, while the right one is associated with the host galaxy.
• Figure 3: The multi-band light curves of SN 2024abfl. The phase represents days relative to the date of explosion, $t_0=60627.27$ MJD.
• Figure 4: The V-band light curve of SN 2024abfl compared with other SNe IIP. (1) 2014MNRAS.439.2873S, (2) 2015MNRAS.450.3137T, (3) 2015MNRAS.450.2373B, (4) 2016ApJ...832..139H, (5) 2018MNRAS.479.2421D, (6) 2018MNRAS.475.3959H, (7) 2023ApJ...954..155T, (8) 2022ApJ...930...34T.
• Figure 5: Top panel: Logarithmic bolometric luminosity ($L_{\mathrm{bol}}$) from observed fluxes. Middle panel: Evolution of the blackbody temperature ($T_{\mathrm{BB}}$). Bottom panel: Evolution of the blackbody radius ($R_{\mathrm{BB}}$). All parameters are shown as a function of days since explosion (MJD 60627.27).