Containing dust and debris resembling an asteroid belt, the Fomalhaut disk is evidence of a complex and active planetary system. One of the brightest stars in the night sky, Fomalhaut is 25 light-years from Earth and 16 times brighter than the Sun. Moreover, it is only a few hundred million years old. The star is surrounded by a large disk of dust and debris, which is its most striking feature.
This disk was discovered in 1983 by NASA's Infrared Astronomy Satellite, and in visible light by the Hubble Space Telescope in 2004. It is comparable to the asteroid belt and Kuiper belt in our own solar system.
It is not surprising that such disks are found around young stars. They form when a swirling cloud of gas reaches a threshold size, mass, or density and collapses under its own gravity.
They are byproducts of angular momentum conservation as stars form. The solar nebula, a collapsing cloud, flattens into a disk as it condenses. Initially, the solids inherited from the gas cloud are small—probably only a few microns in size. But after a few million years, planets form from dust and rocky matter.
Hubble was able to capture the clear features of Fomalhaut's outermost belt, largely because the star's bright periphery is illuminated by the star's great brightness. However, the internal structure of the disk was completely overlooked by the telescope.
The Mid-Infrared Instrument of the James Webb Space Telescope (JWST) has now been used by András Gáspár (University of Arizona) and colleagues to fill in these interior details. The dusty formations seen are significantly more complex than the asteroid belts in our own solar system, as previously demonstrated. In particular, he resolved three intertwined dust belts at 25,5 m IR wavelength, 23 billion kilometers from the star and separated by gaps. This is 150 times farther from the Earth than from the Sun.
source: physicstoday
Günceleme: 18/05/2023 18:56