JWST Reveals Presence of Debris Disk in Beta Pictoris System; Dusty ‘Cat’s Tail’ Suggests Recent Massive Collision

Since the 1980s, Beta Pictoris has been a fascinating subject for scientists, and it still holds surprises even after decades of study. Just recently, NASA's James Webb Space Telescope has unlocked a new feature of this gravitationally bound system using infrared imaging.

Unveiling the Cat's Tail

Sixty-three light years away from Earth, this young planetary system is estimated to be only 20 million years old and is known for hosting a gas giant called Beta Pictoris b. This young planetary system has gained the attention of experts for being the first to reveal a dust disk captured around a distant star. This disk, formed from the collisions between comets, asteroids, and planetesimals, offers a unique insight into the complex dynamics of cosmic debris in the universe.

Using the Hubble Space Telescope, astronomers have initially imaged a second debris disk inclined about the previously observed outer disk. In the latest study, experts led by Isabel Rebollido of the Astrobiology Center in Spain utilized the Near-Infrared Camera (NIRCam) and Mid-Infrared Instrument (MIRI) of the Webb telescope to explore the composition of the primary and secondary debris disk of Beta Pictoris.

The results of the study exceeded the astronomers' expectations. The research team discovered a sharply inclined branch of dust, shaped like a cat's tail, which extends from the southwest portion of the secondary debris disk.

Rebollido describes Beta Pictoris as a debris disk that has it all. It contains a bright, close star, which can be studied well, and a complex circumstellar environment containing exocomets, a multi-component disk, and two imaged exoplanets. There have been earlier observations from the ground in this wavelength range, but they did not possess the sensitivity and spatial resolution they have with Webb.

Even with Webb or JWST, observing Beta Pictoris mid-infrared was crucial in detecting the cat's tail. This is because this planetary system only appeared in the MIRI data. The team did not expect Webb to reveal the two types of material around Beta Pictoris, but MIRI clearly showed them that the secondary disk and cat's tail material are hotter than the main disk.

According to study co-author Christopher Stark from NASA's Goddard Space Flight Center, the dust that makes the secondary disk and tail must be very dark, preventing researchers from observing it as visible wavelengths. In the mid-infrared range, however, the dust is glowing.

A Hundred-Year-Old Dust Event

It remains a mystery why the shape of the cat's tail is uniquely curved, unlike what is seen in disks around other stars. Rebollido and her colleagues modeled different scenarios to emulate the cat's tail and explore its origins to address this concern.

The research team hypothesized that the cat's tail resulted from a dust production event about a hundred years ago. As explained by study co-author Marshall Perin, something like a collision might have happened, leading to a lot of dust production. At first, the dust followed the same orbital direction as its source but started to spread out later. The light from the star pushed the smallest, fluffiest grains away from the star faster. Meanwhile, the bigger dust particles did not move as much, creating a long tendril of dust.