Never-before-seen images: asteroid belts in another solar system

Asteroid belt

Our knowledge of the universe is based on the observations we can make in our own neighborhood. The solar system is the main reference when we study similar systems, for example, the distribution of planets, the existence of comets, moons and other curious processes. However, due to instrument limitations many of these have not been found in other stars. Thanks to new generation telescopes such as James Webb, astronomers have discovered the first asteroid exocinturon. 

False-color photograph of the asteroid bands discovered by James Webb. Credits: NASA, ESA, CSA, A. Pagan (STScI), A. Gáspár (University of Arizona)

How do asteroid belts form? 

In our solar system there are two main regions where minor objects accumulate. The innermost is known as the main asteroid belt and lies between the orbits of Mars and Jupiter. Meanwhile, beyond Neptune is the Fernandez-Kuiper belt, home to a considerable number of comets and dwarf planets. The locations of these are given by the gravitational interactions between the major planets. 

Current models propose the origin of the solar system, and most other extrasolar systems, as the collapse of large clouds of dust and gas around one or more stars. Interacting gravitationally and magnetically, the so-called protoplanetary disk is formed. With time and thanks to constant mutual perturbations, large agglutinations of material would form, giving way to the planets.. While the debris that failed to coalesce would form the asteroids and later the asteroid belts. 

Fomalhaut belts 

Previously, several collaborations and observations by ALMA, Hubble and Herschel succeeded in detecting and imaging analogs of the Fernandez-Kuiper belt. However, never before had it been possible to resolve in one image the most innermost. This was made possible by James Webb's incredible resolution and sensitivity in the infrared.  


Using the MIRI instrument, which observes in the mid-infrared bands, the thermal glow of a large asteroid cloud forming up to three rings or belts was captured as never before. They surround the star Fomalhaut, the brightest star in the constellation Piscis Australis.  

The three belts are shaped by the gravitational interaction of planets that are not visible in the image, both their size and the separations between them.. This is similar to the way Jupiter organizes the asteroids of the main belt.  

Kuiper belt plot objects of outer solar system
Diagram showing the location of objects identified by the minor body institute in the Kuiper belt.

The discovered belts reach a radius of up to 150 times the average distance between the Earth and the Sun, thus allowing observation by the James Webb instruments. In addition, a zone of higher density and brightness stands out, which is still being studied as a possible cause and consequence in the formation of smaller bodies. 

Postcards from the past 

This discovery offers the possibility of learning more about the formation history of our solar system. Current models put a common ground on the origin of the planets and studying them is the key to understanding the past and future of our neighborhood and only home. 

Francisco Andrés Forero Daza