The outermost ring around Fomalhaut has been known for years, and now two more have been discovered with the space telescope James Webb. They indicate the presence of exoplanets.
The space telescope James Webb has achieved the most detailed image to date of the star system Fomalhaut, showing the presence of three debris rings. According to the European Space Agency (ESA), the structures are much more complex than anything we know from the solar system. At the same time, there are now new indications of exoplanets there. In total, there are three nested belts around the star, which is located 25 light-years away, extending up to a distance of 23 billion kilometers. That is approximately 150 astronomical units, or three times the maximum distance between the dwarf planet Pluto and the Sun. Additionally, a possible remnant of a major collision has been discovered.
Hope for a "really interesting planetary system"
Fomalhaut has fascinated the astronomy community for years, with several telescopes capturing images of the outermost ring of the brightest star in the constellation Southern Fish. However, the inner structures were previously hidden, according to the ESA. Only with the Mid-Infrared Instrument (MIRI) on board the space telescope James Webb were they finally resolved. The clearly visible gaps between the rings are likely indications of exoplanets yet to be discovered between them, says George Rieke of the University of Arizona. "I don't think it's a big step to say that there is a really interesting planetary system around the star," the ESA quotes the MIRI chief scientist as saying.
The image shows the already known outermost ring, which is reminiscent of the Kuiper Belt in the solar system. It begins beyond Neptune and consists of icy objects. Such belts have also been detected around other stars. Only the JWST can now also image the inner rings around Fomalhaut, which are more reminiscent of the asteroid belt. Meanwhile, the space telescope has imaged the "large dust cloud" in the outermost ring, which could be the result of a collision between two protoplanetary objects. Interestingly, it is a different object than the one that was first interpreted as an exoplanet years ago.
The object initially known as Fomalhaut b, which was believed to be an exoplanet, even received the name "Dagon" in 2015. The object was discovered with the Hubble Space Telescope in 2008, but disappeared from images in subsequent years. It is now believed to have been an expanding cloud of small dust particles resulting from a giant explosion. This likely occurred shortly before the first image was taken in 2004, and it is thought that two comet-like objects with diameters of around 200 kilometers were destroyed. It had been previously thought that such collisions only occurred in this area about every 200,000 years, but the discovery of another such cloud suggests this estimate needs to be revised.
The impressive image captured by the James Webb Space Telescope once again highlights the instrument's capabilities, which have only been gathering scientific data for less than a year. The device, operated by the space agencies NASA, ESA, and CSA, was launched on December 25, 2021. After a complex self-deployment procedure, it arrived at the Lagrange point L2 a month later. Here it looks out into space away from the Sun, Earth, and Moon, so their thermal radiation does not interfere with the infrared telescope. A huge sunshield blocks this radiation. The image of Fomalhaut is now presented in a paper published in the scientific journal Nature Astronomy.
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