Scientists have used the James Webb Space Telescope to make a very detailed study of the chemical composition of the ultra-hot planet WASP-121b. They show that this gas giant must have formed in much colder regions of its star system.
Gas giant WASP-121b
A team of scientists led by astronomers Thomas Evans-Soma and Cyril Gapp has recently been able to accurately determine the content of water vapor, carbon monoxide, methane, and silicon in the atmosphere of the exoplanet WASP-121b. Thanks to this, they learned interesting things about the place where it actually formed.
WASP-121b is a well-known planet that has been the subject of much research for quite some time. Its peculiarity lies in the fact that it is an ultra-hot gas giant that orbits its star in just 30.5 hours and is in a state of tidal capture. Because of this, one side of the planet is always “looking” at the star, heating up to about 3000°C, while the opposite side, although constantly in the shade, remains extremely hot – about 1200°C.
Of course, under such conditions, many of the substances that are in a solid state in our country are gases. Therefore, the composition of the atmosphere and its behavior is quite unusual, and it was this that James Webb studied with his infrared spectrograph.
Born in the vicinity
The detection of water vapor and methane in the atmosphere of WASP-121b led to the conclusion that this planet was not born in the place where it is now. Like all worlds, it was formed in a protoplanetary disk, and in such structures, the chemical composition varies greatly from the center to the edges.
Like the other planets, WASP-121b was formed from planetesimals, the primary clumps of material in the protoplanetary disk. These bodies stuck together to form the planet’s embryo, which eventually heated up, partially melted, and underwent complex transformations. The specific scenario of formation depended on the conditions in the part of the disk where the planet emerged. In the case of WASP-121b, scientists concluded that its formation took place in a region where it was warm enough for methane to evaporate, but water was still in a solid state.
In the Solar System, this would correspond to a space somewhere between the orbits of Jupiter and Uranus, so WASP-121b was born somewhere closer to the edge of its star system. But over time, it migrated and eventually ended up in a close orbit around its star, where we see it now.
Provided by phys.org
