UNITED STATES: Astronomers using NASA’s James Webb Space Telescope have discovered a complex structure of dusty belts around the nearby young star Fomalhaut, located in the southern constellation Piscis Austrinus. The dusty belts, the debris from collisions of larger bodies similar to asteroids and comets, extend to 14 billion miles (23 billion kilometres) from the star and are frequently described as ‘debris disks.’
The new observations, which were made in infrared light, revealed three nested belts around the star, including two inner belts that had never been seen before. The outermost belt is roughly twice the scale of our solar system’s Kuiper Belt, which contains small bodies and cold dust beyond Neptune.
“I would describe Fomalhaut as the archetype of debris disks found elsewhere in our galaxy because it has components similar to those we have in our own planetary system,” said András Gáspár of the University of Arizona in Tucson, the lead author of the new paper describing these results.
The Hubble Space Telescope, Herschel Space Observatory and the Atacama Large Millimeter/submillimeter Array (ALMA) have previously taken sharp images of the outermost belt). However, none of them found any structure interior to it. NASA’s James Webb Telescope has resolved the inner belts in infrared light for the first time.
“Where Webb really excels is that we’re able to physically resolve the thermal glow from dust in those inner regions. So you can see inner belts that we could never see before,” said Schuyler Wolff, another team member at the University of Arizona.
The new observations also reveal a great dust cloud, which may be evidence of a collision occurring in the outer ring between two protoplanetary bodies. This is a different feature from a suspected planet first seen inside the outer ring by NASA’s Hubble in 2008. Subsequent Hubble observations showed that by 2014 the object had vanished. It’s plausible that this newly discovered phenomenon, like the one before it, is an expanding cloud of incredibly fine dust from two frozen bodies that collide.
“These belts around Fomalhaut are kind of a mystery novel: Where are the planets?” said George Rieke, another team member and U.S. science lead for Webb’s Mid-Infrared Instrument (MIRI), which made these observations. “I think it’s not a very big leap to say there’s probably a really interesting planetary system around the star.”
The idea of a protoplanetary disk around a star goes back to the late 1700s when astronomers Immanuel Kant and Pierre-Simon Laplace proposed that the Sun and planets are formed from a rotating cloud of gas and dust. Webb’s new observations of Fomalhaut’s complex debris disks provide fresh insights into the formation and evolution of planetary systems.
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