The glories of an exoplanet - Pieuvre.ca

2024-04-15 00:13:08

Scientists did not expect to observe a delicate ballet of light on WASP-76b, a so-called hellish planet. A demonstration of the growing power of astronomical tools.

WASP-76b’s environment is not very hospitable, to say the least: this planet is located very close to its star — 1/12 the distance between the Sun and Mercury — and has a side permanently exposed to heat. With the result that the temperature there reaches 2400°C, describes the Scientific American. The other side is plunged into perpetual night. On this planet, iron therefore exists in the form of vapor and when this is transported by the winds towards the dark side, it condenses to form a rain of molten iron.

However, it is on this hellish planet that scientists have observed a rainbow-like phenomenon: a glory. This is what we call an optical phenomenon made up of concentric rings, which is caused by the passage of light in the very narrow space which separates the suspended particles: this creates diffraction.

Except that very specific conditions are necessary to witness glory. The atmosphere must be composed of completely spherical, uniform particles that are illuminated directly by the star’s light. The observer must also be in exactly the right place.

We can admire glories on Earth and some have also been seen in the atmosphere of Venus. However, this is the first time that scientists have managed to detect this optical phenomenon on a planet in another solar system – an exoplanet.

This observation was made possible thanks to the project CHEOPS, a mission led by the European Space Agency. This discovery shows that it is now possible to detect subtle phenomena on the surface of these distant planets. Astronomers’ tools would in theory be able to recognize similar light disturbances that would be caused by the presence of oceans or large areas of water on exoplanets, project leaders say in their press release. Their study was published in the journal Astronomy & Astrophysics.