In the grand theater of the universe, stars live brilliant but finite lives. Some fade quietly, while others die in spectacular explosions that light up galaxies and rewrite cosmic history. Among the most studied stellar deaths are type Ia supernovae—cataclysmic events so powerful they serve as cosmic mile markers, helping astronomers measure the expansion of the universe. But hidden within this class is a much rarer and stranger cousin: the type Iax supernova.
One such celestial rarity appeared in 2022 within the spiral arms of the galaxy NGC 3938, about 72 million light-years away. This event, named SN 2022xlp, has since become the subject of an international research campaign. Through careful observation, astronomers have uncovered clues that may help answer long-standing questions about the nature of these enigmatic explosions.
The Strange Family of Type Iax Supernovae
To understand SN 2022xlp, we must first step back into the broader family of supernovae. Most type Ia supernovae occur when a white dwarf—a dense, Earth-sized remnant of a star that has exhausted its fuel—steals material from a companion star. When the white dwarf accumulates enough matter, it undergoes runaway nuclear fusion, blowing itself apart in an almost uniform explosion. Because of their consistency, type Ia supernovae are often used as “standard candles” to calculate astronomical distances.
But type Iax supernovae are the rebels of this group. Instead of obliterating the white dwarf entirely, they seem to fizzle rather than detonate, leaving behind a remnant star. Their explosions are dimmer, slower, and less energetic than their type Ia cousins. For astronomers, these peculiar events are both a puzzle and an opportunity: they may reveal a missing link in the story of stellar death, helping us understand not just how stars die, but how galaxies evolve.
The Discovery of SN 2022xlp
When SN 2022xlp first appeared in 2022, its early spectral fingerprint hinted that it belonged to this rare subclass. Unlike ordinary type Ia supernovae, it was noticeably dimmer and evolved more quickly in color. Its peak absolute brightness was measured at −16.04 magnitudes—a value that puts it squarely in the middle ground of Iax supernovae. This made it especially intriguing because only one other event, SN 2019muj, has ever been studied in detail at such an intermediate luminosity.
Recognizing its rarity, a team led by Dominik Bánhidi of the University of Szeged in Hungary launched a detailed observational campaign. Using both ground-based and space telescopes, they followed the supernova for more than two months after its explosion. Their work, published in September 2023, offers the clearest view yet of this strange cosmic firework.
Tracking the Supernova’s Light and Color
One of the key ways astronomers study supernovae is by tracking their light curves—the way their brightness changes over time. SN 2022xlp revealed a V-band peak at −16.04 magnitudes, confirming it as an intermediate-luminosity Iax event.
But brightness alone wasn’t the whole story. The team also observed how the supernova’s color shifted over the weeks. In its early days, the explosion radiated with a hot, bluish hue, but as time passed, it grew redder. This color evolution, caused by the cooling of the ejected material, was unusually fast. Within less than a month, the light shifted by about 1.5 magnitudes—a striking transformation that offered new insight into the physics of its fading glow.
Interestingly, when compared with other Iax supernovae, the team found that brighter explosions tend to exhibit more dramatic color shifts. This relationship could provide a valuable clue for classifying and understanding the diversity of these rare events.
The Energy Behind the Explosion
Numbers alone cannot capture the grandeur of a star exploding, but the figures astronomers calculated for SN 2022xlp give us a glimpse of its power. The supernova’s peak bolometric flux—the total energy output across all wavelengths—was an astonishing 887 duodecillion ergs per second. To put that into perspective, for a brief moment, SN 2022xlp outshone billions of stars combined.
The analysis also revealed that the explosion produced about 0.02 times the mass of the Sun in radioactive nickel. This isotope is crucial because its decay powers much of the supernova’s light. Meanwhile, the total explosion energy was estimated at 20 quindecillion ergs, with about 0.14 solar masses of material ejected into space. Though smaller in scale than typical type Ia explosions, these values are still immense, reflecting the sheer violence of stellar death.
A Cosmic Sibling: Comparing SN 2022xlp to SN 2019muj
Astronomy often advances through comparison, and SN 2022xlp found a cosmic sibling in SN 2019muj, the first intermediate-luminosity Iax supernova studied in detail. Both explosions shared strikingly similar light curves, spectra, and energy outputs. Together, they provide a new category of data for researchers to explore—a middle ground between the faintest and brightest of the Iax family.
This growing body of evidence suggests that type Iax supernovae may follow a broader spectrum of behavior than previously thought, with intermediate-luminosity events forming a bridge between extremes. Understanding this continuum may eventually help scientists piece together the full evolutionary pathways of white dwarfs on the brink of destruction.
Why This Matters for Astronomy
At first glance, studying a dim, rare supernova in a distant galaxy might seem like a small detail in the vastness of space. But such discoveries carry weight far beyond their apparent obscurity. Type Iax supernovae could hold the key to unlocking how white dwarfs interact with their binary companions, how stellar remnants evolve after partial explosions, and why some stars survive blasts that should, by all accounts, destroy them.
Moreover, these studies enrich our understanding of cosmic chemistry. The heavy elements forged in such explosions are scattered into space, eventually becoming part of new stars, planets, and even life itself. In this sense, supernovae are not just cosmic fireworks; they are creators of the elements that make our world possible.
The Continuing Journey of Discovery
SN 2022xlp is just one star among countless billions, yet its story is extraordinary. By lingering in the twilight zone between faint and bright explosions, it has forced astronomers to rethink the diversity of stellar deaths. Each observation adds a new brushstroke to the vast cosmic painting, revealing that the universe is more varied and surprising than we could ever imagine.
As telescopes grow more powerful and surveys more precise, more Iax supernovae will surely be found. With each discovery, we come closer to answering profound questions about the life cycles of stars, the mechanics of explosions, and the origins of the elements that make us who we are.
In the end, SN 2022xlp is more than just data points on a light curve. It is a reminder that even in the distant corners of space, far beyond the reach of our eyes, the universe continues to write stories of creation, destruction, and rebirth—stories that, in their own way, are also our own.
More information: D. Bánhidi et al, SN 2022xlp: The second-known well-observed, intermediate-luminosity Iax supernova, arXiv (2025). DOI: 10.48550/arxiv.2509.07717
