Hubble images the Cat’s Tail debris feature around Beta Pictoris

University of Arizona researchers led by doctoral student Arin Avsar used Hubble to image the Cat’s Tail in scattered visible light for the first time, revealing a curved dust feature in the Beta Pictoris debris disk roughly 63 light-years from Earth in Pictor across six observing epochs between 2012 and 2025.

The Cat’s Tail extends roughly 500 astronomical units from the star. Other coverage describes the feature as stretching across as much as 1,000 astronomical units, about 93 billion miles.

University of Arizona doctoral student Arin Avsar led the research showing the Cat’s Tail is thought to be the aftermath of a collision between large bodies comparable to Pluto. Avsar and collaborators estimate the collision occurred roughly 100 years ago based on angular extent and radiation-pressure timescales.

Grain mass modeling by Avsar and collaborators placed progenitor bodies at inferred radii between 600 and 800 kilometers, putting them in Pluto and Charon territory and overlapping dwarf planets such as Makemake and Eris. An earlier JWST-only analysis placed the bodies at 100 to 500 kilometers in radius; Hubble pushes the estimate upward toward dwarf-planet-class objects.

The structure is dark because organic refractory material absorbs visible light, and long carbon chains make the grains quite black, explaining why shorter-wavelength telescopes missed it. Dust in the Cat’s Tail is composed of roughly 96 percent organic refractory material by grain volume, with a modeled range of 85 to 99 percent, according to Avsar and collaborators.

“We think the Cat’s Tail has eluded our observations in visible light until now because of what it’s made of,” Avsar explained.

JWST first confirmed the Cat’s Tail in 2024 using MIRI coronagraphy, but the feature had remained invisible at shorter wavelengths until Hubble’s scattered optical detection. The Cat’s Tail appears shorter in Hubble visible-light images than in JWST infrared observations because Webb measures thermal emission while Hubble detects reflected starlight that weakens farther from the star.

Researchers revised the Cat’s Tail’s three-dimensional geometry, finding it may extend straight sideways relative to Earth in the star’s sky plane rather than stretching behind the star. Earlier interpretations suggested the Cat’s Tail extended far behind Beta Pictoris from Earth’s perspective. New modeling indicates the trail may lie primarily across our line of sight rather than deep into the background, though its precise three-dimensional arrangement remains model-dependent.

“It’s essentially in the same plane of the sky as the star and possibly extends a little bit behind it.”

The dust grains are micron-sized and extremely porous or fluffy, and researchers do not fully understand how such small grains can be so porous. The grains have porosity between 0.55 and 0.93, indicating loosely packed aggregates rather than dense rocky fragments, and favor micron-to-millimeter sizes that radiation pressure can push outward.

Kevin Wagner, a NASA Sagan Postdoctoral Fellow at Steward Observatory and a co-author on the Cat’s Tail study, proposed high-velocity vaporization and recondensation as one explanation. He proposed that extreme collision velocities could vaporize carbon-rich material into gas that later recondensed into highly porous, fluffy micron-sized particles. The high-velocity vaporization and recondensation scenario remains a proposed explanation rather than a confirmed reconstruction of the collision.

The team combined more than 14 years of Hubble and JWST observations and computer modeling to map the Cat’s Tail in fine detail. Avsar and collaborators published “Deep HST/STIS Coronagraphic Imaging of the β Pictoris Debris Disk” on Oct. 7, 2026 in The Astrophysical Journal Letters. The Avsar 2026 team used Hubble’s STIS coronagraph 50CORON mode, specifically the 10-arcsecond and 5-arcsecond occulting-bar apertures, across six observing epochs between 2012 and 2025 to suppress the central star.

The STIS-to-MIRI flux ratio of the Cat’s Tail falls between 0.1 and 0.4 percent, a diagnostic that rules out bright silicate grains and points to dark absorbing carbon compounds. Mie scattering calculations based on the Bruggeman effective-medium mixing rule and a Markov Chain Monte Carlo algorithm with 32 walkers, 10,000 steps and 1,000 burn-in steps per run translated the STIS-to-MIRI flux ratio into grain composition. The STIS-to-MIRI flux-ratio technique is generalizable to nearby debris disks bright and close enough to resolve, combining Hubble’s STIS coronagraph in scattered optical light with JWST’s MIRI coronagraph in mid-infrared thermal emission.

Beta Pictoris b and c are confirmed giant planets, and Beta Pictoris d is a candidate world of around 2.4 Jupiter masses from a separate 2026 study; the star itself is about 20 million years old. Hubble identified a previously unseen warp in Beta Pictoris’s dust halo, likely caused by gravitational interaction with Beta Pictoris b, a gas giant about 10 times Jupiter’s mass.

A 2025 secular dynamics model by Sefilian and collaborators attributes the outer halo warp to secular perturbations from an inclined planet, possibly Beta Pictoris c or d, acting on outer disk material over millions of years. Avsar and collaborators report new spatial constraints on the warp from STIS imaging, extending previous Hubble archive measurements.

Bradford Smith and Richard Terrile imaged the Beta Pictoris disk in 1984, the first direct photograph of any extrasolar debris disk.

Debris disks around dozens of nearby young stars have been imaged at mid-infrared wavelengths by JWST, many with resolved substructure hinting at recent or ongoing collisions. Beta Pictoris debris disks are thought to be in the final stages of planet formation, making them natural laboratories for clues about our own young solar system.

SciTechDaily says the Kuiper Belt may have held hundreds of Pluto-sized objects around the time it was about 20 million years old, in a region far denser than it is now. A 2014 ALMA detection found a carbon monoxide gas clump at roughly 80 AU southwest of Beta Pictoris, precisely where the Cat’s Tail originates, and the collision may have released trapped CO and other volatiles.