"Wet Lava Ball" Exoplanet Might Host an Atmosphere, New Clues Indicate

According to recent findings by NASA experts, a rocky exoplanet beyond our solar system potentially possesses an atmosphere.

Discovered in 2020, this exoplanet named TOI-561b is considered a super-Earth. It features scorching temperatures and notably low density, measuring approximately 1.4 times Earth's size. It revolves around its sun-like star in roughly 11 hours, at a distance 40 times closer than Mercury is to our sun. Observations hint at the presence of a planet-wide magma ocean encased in a substantial gaseous envelope.

TOI-561b's unexpectedly low density has left scientists puzzled. It might display a unique structure compared to planets in our solar system, possibly being surrounded by a dense atmosphere—uncommon for a planet with its characteristics. Utilizing advanced methods, scientists gathered data that supports this unexpected hypothesis.

Researchers applied the Near-Infrared Spectrograph to study the planet's temperature on its sunlit side. They projected the planet's temperature would reach about 4,900 degrees Fahrenheit if it lacked an atmosphere. However, readings showed a significantly lower temperature of around 3,200 degrees Fahrenheit.

Merely measuring the temperature is insufficient to confirm atmospheric presence, according to NASA. The cooling effect might stem from either the circulation of thermal energy in a magma ocean or a thin shell of vaporizing rock. Yet, neither explains the stark discrepancy between expected and measured temperatures.

"A substantial atmosphere rich in volatile substances is vital to account for the observations," said Anjali Piette of the University of Birmingham, a co-author of the research published Thursday.

Piette explained that an atmospheric layer could absorb certain light wavelengths, making them undetectable by the spectrograph. Bright silicate clouds might also reflect starlight, contributing to atmospheric cooling.

Tim Lichtenberg from the University of Groningen, another study co-author, mentioned the possibility of an interaction between the atmosphere and the magma ocean. "As gases are emitted to form the atmosphere, the magma ocean could reabsorb them," Lichtenberg stated. This implies that the exoplanet may be significantly richer in volatile compounds compared to Earth, resembling a 'wet lava ball'.

Ongoing studies, fueled by over 37 hours of observation by the Webb telescope, aim to map TOI-561b's temperature profile and investigate its atmospheric composition, promising further insights.

"The exciting part is that the fresh dataset raises more questions than answers," remarked Johanna Teske, the lead author and scientist at Carnegie Science's Earth and Planets Laboratory.