Astronomers Have Made an Unprecedented Detection of Clouds on a Far-Off Exoplanet

Scientists have discovered clouds on a gas giant exoplanet located 520 light years from Earth using data from multiple telescopes. They were able to determine the altitude and structure of the cloud with great precision.
This work will allow us to better understand exoplanet atmospherics and search for worlds with biosignatures or conditions that are hospitable. Weather reports for distant alien planets are also becoming more feasible.

WASP-127b was discovered in 2016 and is the exoplanet at issue. It is a hot, puffy creature that orbits so close to its star its year is only 4.2 days. It is 1.3 times larger than Jupiter and 0.16 times as large as Jupiter.

Its atmosphere is therefore thin and fragile, making it ideal for trying to analyse its contents using the light from its host star.

Romain Allart, an astronomer at the Universit de Montral in Canada, led the team that combined infrared data taken from the Hubble Space Telescope in space and optical data from ESPRESSO on the Very Large Telescope ground-based to see into the atmosphere at different altitudes.

Allart stated that the first time sodium was detected on this type of planet, it was at a lower altitude than expected.

"Second: There were strong water vapour signals in the visible wavelengths, but none at all in the infrared. This suggests that water vapor at lower levels may be being blocked by clouds that are transparent at infrared wavelengths, but opaque at visible wavelengths.

It is difficult to determine the composition of exoplanetary atmospheric atmospheres. Because we don't have direct access to most exoplanets, we must infer their presence from the effects they have upon their host stars. One is the dimming or brightening of the exoplanet when it passes between us, and the star. The star's light dims just a little.

If it does so on a regular basis, that is one sign of an orbiting exoplanet. This information can also be used in other ways. The wavelengths of the spectrum that are visible through the atmosphere of an exoplanet can be absorbed by different elements or the starlight can pass through them. These signatures are called absorption lines and can be decoded to reveal what's in the atmosphere.

Wasp-127b is compared to the Solar System. (David Ehrenreich/Universit de Genve, Romain Allart/Universit de Montral)

Allart and his team used high-resolution absorption data and high-resolution radar data to reduce the cloud height to a surprising low cloud layer at atmospheric pressure of 0.3 to 0.5 millibars.

Allart stated that "we don't know yet the composition of clouds", except that they aren't composed of water droplets as on Earth."

"We are also puzzled as to why sodium is found in such a strange place on the planet." Future research will allow us to understand more about the atmospheric structure and WASP-127b which is proving to have fascinating properties.

A team analysis revealed some interesting facts about WASP-127b's orbit around its host star. The Solar System is a place where everything is in order. All the planets orbit in the Sun's direction, and in a flat plane around its equator. This is due to the way that the Solar System was formed from a disk of material spinning into the spinning baby Sun.

WASP-127b orbits in the opposite direction to its star's spin, but at an extremely sharp angle almost around the star’s poles. It is believed that the system is approximately 10 billion years old. This means that something is certainly going on in this particular area.

Allart stated, "This alignment is unusual for a hot Saturn within an old stellar system, and might be caused from an unknown companion."

These unique characteristics make WASP127b a planet worth studying in the future.

The research was published by Astronomy and Astrophysics. It was presented at the 2021 Europlanet Science Congress.