How Webb imaged the dusty debris disk around the young star Fomalhaut.

 

Astronomers recently used NASA’s James Webb Space Telescope to image the warm dust around a young star, Fomalhaut, in order to study the first asteroid belt ever seen outside of our solar system in infrared light. Surprisingly, they found that the dusty structures are much more complex than the asteroid and Kuiper dust belts of our solar system. In fact, there are three nested belts extending out to 14 billion miles (23 billion kilometers) from the star; which is 150 times the distance of Earth from the Sun. The outermost belt’s scale is roughly twice the scale of our solar system’s Kuiper Belt. The inner belts, on the other hand, had never been seen before and were first revealed by Webb.

Fomalhaut is a young star encircled by two belts of dusty debris, visible to the naked eye as the brightest star in the southern constellation Piscis Austrinus. These dusty belts, which are analogous to asteroids and comets, are known as ‘debris disks’ and are the result of collisions between larger bodies. According to András Gáspár of the University of Arizona, Fomalhaut is considered to be the archetype of debris disks found elsewhere in our galaxy, as it has components similar to those found in our own planetary system. The patterns formed in these rings can help us understand what a planetary system typically looks like, potentially even revealing the presence of suspected planets if a deep enough image is taken.

The Hubble Space Telescope and Herschel Space Observatory, as well as the Atacama Large Millimeter/submillimeter Array (ALMA), have previously taken sharp images of the outermost belt, yet none of them have discovered any structure interior to it. However, the inner belts have now been resolved for the first time by Webb in infrared light. This revelation has allowed us to see these inner belts which were previously never seen before. According to Schuyler Wolff, a member of the team at the University of Arizona, this is where Webb really excels due to its ability to physically resolve the thermal glow from dust from these inner regions.

Hubble, ALMA, and Webb have come together to create a comprehensive view of the debris disks that exist around a variety of stars. Through the combined efforts of all three telescopes, researchers are able to gain insight into both the outer and inner regions of these disks, allowing for the formation of models about how they form and evolve. This collaboration between these powerful tools has created an invaluable resource for researchers in the field.

Based on the evidence provided by Webb images, gravitational forces from unseen planets are responsible for the formation of most belts in various solar systems. Similarly, own solar system is shaped by invisible bodies like Jupiter, Neptune, and potentially others that remain unknown. As more images are collected, we gain insight into the complexities of the solar system and can better understand how it is sculpted by these unseen forces.

Fomalhaut’s dust ring is an impressive discovery, having been first seen in 1983 with the help of NASA’s Infrared Astronomical Satellite (IRAS). This discovery has since been further verified using longer-wavelength observations with submillimeter telescopes, NASA’s Spitzer Space Telescope, and Caltech’s Submillimeter Observatory. This ring is a unique and fascinating astronomical feature that continues to be studied to this day.

The belts around the star Fomalhaut are an intriguing mystery to scientists. George Rieke, the U.S. science lead for Webb’s Mid-Infrared Instrument (MIRI), believes there is likely a fascinating planetary system surrounding the star. Wolff added that they did not anticipate the more complex structure with the second intermediate belt and wider asteroid belt. To astronomers, these gaps and rings suggest the possibility of planets being embedded within them, adding even more mystery to the study of this star. The rings and gaps could be shaped by a planet, meaning the possibilities of what lies beyond the rings are endless.

Webb imaging of the outer ring of the star Fomalhaut revealed a ‘great dust cloud’, which may be evidence for a collision between two protoplanetary bodies. This is distinct from a suspected planet that was seen in the outer ring in 2008 by the Hubble telescope, and had vanished by 2014. Hence, it is suggested that this newly-discovered feature is a cloud of fine dust particles resulting from the collision of two icy bodies. This interpretation is further supported by observations of Fomalhaut’s inner ring, which showed evidence of collisions between icy objects and dust clouds in 2009. Thus, Webb’s imaging of the outer ring and subsequent Hubble observations lend support to the idea of multiple collisions occurring in Fomalhaut’s rings .

The idea of a protoplanetary disk around a star dates back to the late 1700s, when astronomers Immanuel Kant and Pierre-Simon Laplace independently developed the theory that the Sun and planets were formed from a collapsing and flattening rotating gas cloud due to gravity. Debris disks, which form after planets have been formed and the primordial gas has dispersed in the systems, can reveal crucial information about the structure of an exoplanetary system by providing observations of their dust, even reaching down to earth-sized planets and asteroids which are much too small to be seen individually.