SN 2024abfl: A Low-luminosity Type IIP Supernova at the Low-mass End of Core Collapse

Abstract We present optical photometric and spectroscopic observations of the low-luminosity (LL) Type IIP supernova SN 2024abfl. The distance to its host galaxy is highly uncertain, with independent estimates of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>9</mml:mn> <mml:mo>.</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>5</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>2.4</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>2.3</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> Mpc and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mn>15</mml:mn> <mml:mo>.</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>0</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>1.9</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>+</mml:mo> <mml:mn>8.9</mml:mn> </mml:mrow> </mml:msubsup> </mml:math> Mpc. Even adopting the larger distance, the inferred plateau luminosity is only ∼10 41 erg s −1 , placing SN 2024abfl at the extreme faint end of the supernovae (SNe) IIP population. Its light curve exhibits a long-lasting plateau of approximately 110 days. The spectra show exceptionally low expansion velocities, with a Fe ii velocity of ∼1200 km s −1 at 50 days after the explosion, significantly lower than the typical values of ∼2000–5500 km s −1 observed in SNe IIP, placing SN 2024abfl among the slowest-expanding LL SNe IIP. Bolometric modeling yields a synthesized 56 Ni mass of ∼0.002–0.004 M ⊙ , though this estimate remains subject to significant uncertainty owing to the poorly constrained distance. Considering the plateau color and duration, the magnitude drop from plateau to tail, and the progenitor luminosity, we favor a low-mass core-collapse origin for SN 2024abfl.