SN 2026aaiv in NGC 7331 – A Type Ia Supernova
Key Scientific Data
Object type: Type Ia supernova
Official designation: SN 2026aaiv
Initial survey designation: ATLAS26krw
Host galaxy: NGC 7331 – unbarred spiral galaxy
Constellation: Pegasus
Distance from Earth: approximately 45–46 million light-years
Discovery: ATLAS survey, September 1, 2026
Discovery magnitude: approximately 17.3 (ATLAS orange filter)
Right Ascension: 22h 37m 05.63s
Declination: +34° 24′ 35.2″
Redshift: approximately 0.003
Observation date: September 5, 2026
Light-travel time: approximately 45 million years
Description
SN 2026aaiv is a Type Ia supernova discovered in the spiral galaxy NGC 7331, approximately 45 million light-years from Earth, in the constellation Pegasus.
First detected by the automated ATLAS survey on September 1, 2026, at magnitude 17.3, the supernova brightened rapidly during the following days.
This image, captured on September 5, just four days after discovery, documents the appearance of a new point of light within the galaxy, produced by one of the most energetic forms of stellar explosion.
Before and After the Explosion
The comparison shows two observations of NGC 7331 obtained less than two months apart at the same observatory.
The left-hand image, acquired between July 15 and 19, 2026, combines 60 luminance exposures of 300 seconds each. No supernova is visible at the position of the subsequent event.
The right-hand image, captured on September 5, consists of six 300-second exposures and clearly reveals SN 2026aaiv, identified by the arrow.
The comparison provides direct photographic evidence of a transient astronomical event occurring in another galaxy, tens of millions of light-years away.
What Is a Type Ia Supernova?
A Type Ia supernova results from the thermonuclear explosion of a white dwarf, the compact remnant of a star that has completed its normal evolution.
In a binary system, interaction with a companion star or another white dwarf can create conditions that trigger runaway nuclear fusion, releasing enormous amounts of energy and generally destroying the exploding star.
At maximum brightness, a Type Ia supernova can briefly reach a luminosity of billions of Suns, making these events detectable across vast intergalactic distances.
Their characteristic spectra, including absorption features associated with ionised silicon, allow astronomers to distinguish them from supernovae produced by the collapse of massive stellar cores.
Supernovae and Modern Cosmology
Type Ia supernovae are particularly important because their peak luminosities can be standardised using their observed light curves and colours.
This makes them valuable cosmic distance indicators, allowing astronomers to measure distances to galaxies far beyond the Milky Way.
Observations of distant Type Ia supernovae provided crucial evidence for the accelerating expansion of the Universe, a discovery associated with the phenomenon known as dark energy.
These explosions also produce and disperse substantial quantities of iron-group elements, contributing to the chemical enrichment of galaxies and the formation of future stellar systems.
Curiosities
SN 2026aaiv was discovered by ATLAS (Asteroid Terrestrial-impact Last Alert System), a robotic survey originally developed to detect potentially hazardous near-Earth asteroids but also highly effective at identifying astronomical transients.
Remarkably, NGC 7331 had already hosted another reported Type Ia supernova, SN 2025rbs, in the preceding year.
The July reference image makes this observation especially significant: both the pre-discovery and post-discovery photographs were obtained with the same observatory, providing a direct record of the supernova's appearance.
Although the new source resembles an ordinary star in the image, it represents a thermonuclear explosion occurring within a galaxy containing billions of stars.
Looking Back in Time
The light captured from SN 2026aaiv began its journey approximately 45 million years ago, during Earth's Eocene epoch.
At that time, the planet was considerably warmer, mammals were diversifying, and early primates were evolving. Humans and their hominin ancestors did not yet exist.
While life on Earth evolved and entire geological epochs passed, the photons released by the explosion travelled through intergalactic space towards the Milky Way.
On September 5, 2026, a fraction of that light reached the Innumerabili Mondi Observatory, where it was recorded during just 30 minutes of exposure.
The photograph therefore captures the destruction of a distant white dwarf as it occurred approximately 45 million years ago, an event whose light has only now reached Earth.
Image Data
Total integration time: 30m
Integration by filter:
- Luminance: 30m (6 × 300")
Equipment:
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Telescope: Artesky ARTEC 250 Pro
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Camera: Player One Poseidon-M Pro
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Mount: 10Micron GM2000 HPS II
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Filter: Antlia V-Pro Luminance 2"
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Accessories: Pegasus Astro Prodigy Microfocuser, Player One Phoenix Wheel 7×2", WandererAstro WandererCover V4-EC
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Software: Adobe Photoshop, Pleiades Astrophoto PixInsight, Stefan Berg Nighttime Imaging 'N' Astronomy (N.I.N.A. / NINA)
Comparison image:
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Before: 60 × 300" luminance exposures – July 15–19, 2026
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After: 6 × 300" luminance exposures – September 5, 2026
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Supernova: SN 2026aaiv, indicated by the arrow
For further details and the full-resolution image, visit AstroBin: