This article has been reviewed according to Science X's editorial process and policies. Editors have highlighted the following attributes while ensuring the content's credibility: A rocky lava planet once thought to be too extreme to have an atmosphere appears to be wrapped in one with a reflective layer of vaporized silicate mineral clouds, the same family of compounds that make up quartz and sand. University of Waterloo Physics and Astronomy Professor Lisa Dang and collaborators used the James Webb Space Telescope(JWST) to observe the lava planet TOI-561 b for 37 hours, capturing nearly four complete trips of the planet around its star.
The paper, "A Highly Reflective Atmosphere on the Lava World TOI-561 b Revealed by JWST/NIRSpec Phase Curve," was published in The Astronomical Journal. "We measured how the planet's brightness and heat changed throughout its orbit," says Dang. "This technique, known as a phase curve, revealed that the planet reflects a significant amount of light from its star, and that heat is being redistributed around the planet instead of only on the sunlit side.
Together, these point to the presence of an atmosphere." The first study found the dayside was far cooler than expected for a bare, dark rock this close to its star. That missing heat could either be carried around to the night side or reflected away before the planet ever absorbed it. By watching the full orbit, the team got the first look at the night side, which always faces away from the star, and found it isn't warm enough to account for the difference.
Instead, TOI-561 b must reflect roughly three-quarters of the starlight that hits it, comparable to Venus. To explain this brightness, the team compared the observations with a computer simulation of the planet's climate. These suggest that clouds made of silicate minerals, including silicon dioxide (SiO2) and magnesium silicate (MgSiO3), could form on the planet's dayside and act like sunscreen.
By reflecting starlight and keeping the planet cooler, the clouds may help the planet hold onto an atmosphere that would otherwise be stripped away. The results build on earlier evidence by Dang and collaborators that TOI-561 b possesses a thick atmosphere, likely replenished by gases released from its molten interior. What that atmosphere is made of remains an open question.
It could be a dense blanket of carbon dioxide, like a much hotter version of Venus, or it could be rich in sulfur dioxide, a gas released from Jupiter's volcanic moon. The planet has an ocean of molten rock covering its surface, which could act as a planet-wide volcano that is constantly feeding its atmosphere. "The next big question we will seek to answer is whether TOI-561 b's atmosphere resembles Venus or an extreme Io.
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