Astronomers Detected Clouds on Distant Exoplanet WASP-127b, Revealing the Upper Structure of Its Atmosphere

Dr. Romain Allart presented during the Europlanet Science Congress (EPSC) 2021 the result of their team's findings on the upper structure of the exoplanet WASP-127b. Phys.org reported that the team of international astronomers detected floating puffs of unknown composition on the planet's atmosphere, which they believe could be clouds.

They combined the Hubble Space Telescope data and visible measurements from the Echelle SPectrograph for Rocky Exoplanets and Stable Spectroscopic Observations (ESPRESSO) at the European Southern Observatory's Very Large Telescope in Chile that allowed them to observe the clouds.

WASP-127b: The Large, Fluffy Exoplanet

According to NASA, WASP-127b is a gas giant planet located more than 525 light-years away from Earth and orbits a G-type star. It is 1.3 times larger than Jupiter and weighs one-fifth of the mass of the Solar System's largest planet. WASP-127b takes about 4.2 days to complete a revolution.

Discovered in 2016, astronomers observed that the large fluffy exoplanet orbits closely to its host star. That is why its surface temperature could reach 2,012 degrees Fahrenheit (1,100 degrees Celsius), making it a "hot Saturn" planet.

Phys.org reported that WASP-127b receives 600 times more irradiation than Earth because of its location relative to its host star. This also makes WASP-127b one of the fluffiest exoplanets scientists have ever discovered. Its fluffy characteristic makes it easier for astronomers to observe it and make it an ideal candidate for working on atmospheric characterization on exoplanets.

The recent observation of the clouds of this large and fluffy exoplanet has yielded unexpected results that surprised astronomers, particularly on the upper structure of its atmosphere.

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Combining Data From Space- and Ground-Based Telescopes

Digital Trends reported that the exoplanet WASP-127b is one of the least dense exoplanets in the universe and was unlike anything in the Solar System. The international team of astronomers has combined space- and ground-based data to identify the clouds floating in the planet's atmosphere.

Researchers found sodium in WASP-127b's atmosphere. But unlike what researchers expected, they detected the sodium at a lower altitude. Lead author Allart said that they are unsure yet of the cloud's composition, unlike the clouds on Earth, which are composed of water droplets.

Moreover, they found water vapor signals in the infrared but nothing on the visible wavelengths, implying that clouds screen them. Allart said they are still puzzled by the presence of sodium in the planet's atmosphere, but further research could help understand more of the planet's atmospheric structure.

Aside from the odd sodium present in the clouds, they also observed that the planet orbits in the direction opposite its star and does so in an unusual plane rather than the typical equatorial plane that most planets have. The team thinks that this might be caused by an unknown companion, given that it belongs to an old stellar system.