Imagine a planet the size of Earth that is not at all like Earth. Half of this world is locked in perpetual day, the other half in perpetual night, and it’s carpeted with active volcanoes. Astronomers discovered this planet.
The planet, named LP 791-18d, orbits a small red dwarf star about 90 light-years away. The volcanic activity makes the discovery particularly notable to astronomers because volcanic activity facilitates interaction between the inner and outer worlds.
Why is volcanic activity important? It is the main source contributing to a planetary atmosphereAnd with the atmosphere you can have a surface liquid waterIt’s a condition for preserving life as we know it, said Stephen Kane, an astrophysicist at the University of California, Riverside.
Astronomers already knew about two other worlds in this star system, LP 791-18b and c. the outer planetc, is about 2.5 times the volume of Earth, and about nine times its mass.
During each orbit around the star, planets c and d pass close to each other. As they do, planet c’s massive size produces a gravitational tug that makes planet d’s orbit more elliptical, rather than perfectly circular. These deformations in orbit create friction that heats up the planet’s interior, producing heat volcanic activity on the roof.
Researchers found the planet using data from NASA’s TESS satellite and the retired Spitzer Space Telescope. Kane was part of the team that conducted the original TESS observations, and co-authored a paper on the newly discovered planet published in the scientific journal nature.
The other major feature of the planet, as shown in the paper, is the fact that it does not rotate.
“LP 791-18d is tidally closed, which means that the same side is constantly facing its star,” said Bjorn Bencke, co-author of the paper and professor of astronomy at the Trottier Institute for Exoplanet Research, based at the University of Montreal.
“The day side is likely to be very hot on the surface of the liquid water. But the amount of volcanic activity that we suspect is happening across the planet could preserve the atmosphere, which could allow water to condense at night,” Beneke said. .
Although the presence of many constantly erupting volcanoes would likely render the planet uninhabitable, their presence provides new information about evolution.
“The big question in astrobiology, the field that extensively studies the origins of life on and beyond Earth, is whether tectonic or volcanic activity is necessary for life,” said Jessie Christiansen, author of the paper and a research scientist at Caltech.
“In addition to the potential for providing the atmosphere, these processes could produce materials that would otherwise sink and get stuck in the crust, including those we think are important to life, such as carbon,” Christiansen said.
The recent discovery of active volcanoes Venus also shows that Earth-sized planets can continue to add to their atmospheres, with or without plate tectonics.
The main components of volcanic emissions are carbon dioxide and Water vaporAnd Greenhouse gases It can help keep the planet warm. On Venus Carbon Dioxide It remained in the atmosphere, driving the planet into a runaway greenhouse state.”
“today, surface temperatures On Venus, it’s over 850 degrees Fahrenheit—as hot as a wood-fired pizza oven—and the odds of life there are slim. But it may not always have been this way.”
“Volcanoes may be a big piece of the puzzle about what really happened on Venus. Planets like LP 791-18d can provide important insights into how volcanism has shaped planetary environments over time, including Venus and Earth.”
Björn Benneke, a temperate Earth-sized planet with tidal heating passing through the star M6, nature (2023). DOI: 10.1038/s41586-023-05934-8. www.nature.com/articles/s41586-023-05934-8
University of California – Riverside
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