When a star in the nearby galaxy NGC 2146 exploded in late 2024, it barely registered by supernova standards. The blast, cataloged as SN 2024abfl, was roughly 100 times fainter than a typical stellar explosion and ejected material at a fraction of the usual speed. But what it lacked in power, it made up for in persistence: its light held steady on a dim plateau for about 110 days, roughly 10 percent longer than the textbook benchmark for its class. Three independent research teams have now dissected the event, and their combined work paints SN 2024abfl as one of the weakest core-collapse supernovae ever studied in detail, a find that could reshape how astronomers count stellar deaths across the cosmos.
A faint explosion under a microscope
SN 2024abfl belongs to the Type IIP category, supernovae produced when massive stars with thick hydrogen envelopes collapse and rebound. The “P” stands for “plateau,” a phase during which the supernova’s brightness holds roughly constant as a cooling wave recedes through the ejected hydrogen. For most Type IIP events, that plateau lasts about 100 days. SN 2024abfl stretched it to approximately 110 days, according to the primary study led by Li et al. and accepted by The Astrophysical Journal as of early 2026.
The numbers tell the story of a remarkably weak blast. At 50 days after explosion, the iron lines in SN 2024abfl’s spectrum were expanding at just 1,200 kilometers per second, well below the 3,000 to 5,000 km/s range typical of normal Type IIP events. Its plateau luminosity hovered near 1041 ergs per second, placing it in the same dim company as SN 2005cs and SN 1997D, two of the most famous low-luminosity supernovae previously studied. NGC 2146 sits at a redshift of roughly 0.003, only about 55 million light-years away, close enough for telescopes to track the light curve and spectral evolution in fine detail.
Pre-explosion archival images of the site revealed a red supergiant progenitor candidate, exactly the type of star theory predicts for a Type IIP supernova. The detected source is consistent with a star near the lower mass boundary for core collapse, likely in the range of 8 to 12 solar masses, though pinning down the exact figure depends on assumptions about the star’s rotation, metal content, and how much mass it shed before exploding.
Three teams, one explosion, some disagreements
The Li et al. paper is not the only analysis. A separate study posted in January 2026 focused on signs that SN 2024abfl’s early brightening was shaped by the blast wave slamming into dense gas the star had expelled shortly before death. That team measured a plateau closer to 125 days and estimated the explosion forged about 0.01 solar masses of nickel-56, the radioactive isotope whose decay keeps a supernova glowing after the plateau ends. A third effort by Wyatt et al. arrived at a slightly lower nickel yield of roughly 0.009 solar masses while also modeling the ejecta mass, progenitor radius, and kinetic energy.
Both nickel figures are tiny. A normal Type IIP supernova produces on the order of 0.05 to 0.1 solar masses of nickel-56. SN 2024abfl made roughly a tenth of that, consistent with a star that barely mustered enough energy to blow itself apart rather than collapsing quietly into a black hole.
The 15-day gap between the two plateau measurements has not been resolved. It matters because plateau duration is tied to the mass and energy budget of the ejected material: a longer plateau can signal a more massive hydrogen envelope, a lower explosion energy, or both. Differences in how each team defined the plateau’s start and end points, along with systematic uncertainties in distance and dust extinction, likely account for part of the discrepancy. But until the teams reconcile their methods, the exact plateau length remains an open question.
What the missing data could reveal
One significant gap in the current picture is the absence of X-ray and radio observations. The circumstellar-interaction hypothesis, the idea that SN 2024abfl’s early light was boosted by a collision with pre-existing gas, rests primarily on subtle optical clues: asymmetric line profiles and excess emission during the supernova’s rise. X-ray or radio detections would provide much stronger, independent confirmation that dense material surrounded the star. Without them, alternative explanations remain on the table, including asymmetric mixing of radioactive nickel into the outer ejecta or unusual opacity behavior in the hydrogen envelope.
Late-time imaging could also settle the progenitor question definitively. If the red supergiant candidate identified in archival photos has vanished from the explosion site, that would confirm it was the star that died. If it is still there, astronomers would need to reconsider which star actually exploded.
Why a dim supernova matters for the bigger picture
SN 2024abfl is not just a curiosity. If low-mass red supergiants routinely produce faint, slow-evolving explosions like this one, then modern supernova surveys may be systematically missing a significant fraction of core-collapse events in the local universe. Faint supernovae are hard to spot, and some stars at the low-mass boundary may collapse without producing a visible explosion at all, falling directly into black holes or neutron stars with little outward fanfare.
An undercount would ripple through several areas of astrophysics. Estimates of how quickly neutron stars form, how galaxies build up heavy elements, and where the dividing line falls between stars that explode and stars that implode all depend on getting the supernova rate right. A Zwicky Transient Facility census of hundreds of Type IIP supernovae has begun mapping the luminosity function for this class, providing the statistical backdrop against which SN 2024abfl stands out. But the faintest events remain the hardest to catalog, and each well-studied example helps calibrate what surveys are missing.
For now, the broad conclusions about SN 2024abfl are on solid ground. It was unusually faint and slow. It almost certainly came from a red supergiant near the minimum mass for core collapse. It produced a very small amount of nickel-56. The finer details, the exact plateau length, the role of circumstellar interaction, the precise progenitor mass, are still being worked out across three independent research efforts. That productive tension is exactly how science is supposed to work, and SN 2024abfl, one of the dimmest stellar explosions ever caught in the act, is giving astronomers plenty to argue about at the faint edge of the supernova spectrum.
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*This article was researched with the help of AI, with human editors creating the final content.
