Astronomers have discovered the exoplanet HD 3167 b, which is a world covered in lava. This object is notable because it is relatively cool for its type of planet and, surprisingly, has managed to retain an atmosphere. The planet is located 154 light-years from Earth and orbits its star in just one day.
HD 3167 b is classified as a rocky super-Earth and is the smallest known lava world. Despite its extremely close proximity to its star, observations indicate the presence of an atmosphere, which puzzles researchers, as intense stellar radiation and stellar wind should hinder the retention of a gaseous envelope.
Edwin Knight, a professor of geophysics at the University of Chicago (USA) and one of the study's authors, noted: 'What is striking is that the closer a rocky planet orbits its star, the harder it is for it to have an atmosphere, since it is bombarded by stellar wind and receives more high-energy photons. But it seems many of these lava worlds do have one.'
Brandon Park Coy, the lead author of the study and a graduate student in Knight's group, explained that if the planet lacked an atmosphere, its dayside would be as hot as theoretically possible. However, researchers found the opposite: the planet is 'noticeably cooler than expected at maximum.'
The team concluded that the most likely explanation for the low temperature is precisely the presence of an atmosphere. According to the scientists, the gaseous envelope appears to reflect some of the light received from the star and redistributes heat to the night side of the planet, acting as an energy transfer mechanism between the two hemispheres. Thus, HD 3167 b has become the coolest lava world observed with an atmosphere.
This discovery also raises new questions, as astronomers had previously found atmospheres on other extremely hot lava worlds. This new case suggests that it is unclear under what conditions such planets can form and maintain atmospheres.
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Although HD 3167 b is too hot for life, this is precisely what makes it a valuable source of information about processes occurring on other rocky worlds, including early Earth. Knight emphasized: 'These planets are too hot for life, but by studying them, we can learn about processes that are important for other rocky worlds.'
Coy added that the interest in the planet stems from the possibility of using it as a window into an extremely ancient phase of Earth's history. He stated: 'Even though they are uninhabitable, we are also interested in these types of planets because we believe that primitive Earth could have been very similar to a lava world.'
According to the researcher, in the early history of the Solar System, when rocky planets were forming, they were extremely hot due to the energy released during the impact of planetesimals. Earth went through a phase known as the magma ocean, where its surface was entirely liquid. 'This result allows us to study the conditions that existed in the first millions of years of Earth,' Coy concluded.
This discovery is part of a larger program led by astronomer Megan Weiner Mansfield from the University of Maryland (USA). The project analyzes ten lava worlds to determine the temperature conditions under which these planets tend to develop atmospheres. The findings regarding HD 3167 b also reinforce a growing opinion among researchers: the probability that most lava worlds possess atmospheres.
The study of this planet was published in The Astrophysical Journal Letters. The initial post 'Astronomers discover lava planet that may resemble primitive Earth' appeared on Olhar Digital.
