Two planets were already known around the red dwarf star LP791-18, located 90 light years away: the rocky super-Earth LP791-18b, with a mass 20% greater than that of Earth, and the mini-Neptune . gaseous planet about nine times the mass of Earth.
Today it is published in the magazine Nature the discovery of a third Earth-like planet, LP791-18d, whose orbit around the star is dangerously close to a mini-Neptune. This produces a gravitational interaction that slightly deforms the newfound planet and heats its interior, possibly generating widespread volcanic activity along its surface.
“Planet LP791-18d shows what’s known as tidal coupling, meaning that the same side is constantly facing its star,” said Björn Benneke, a researcher at the Université de Montréal who is leading the study. exist on the surface, but the amount of volcanic activity we suspect across the planet could sustain an atmosphere, which could allow water to condense on the nightside.”
The newly discovered planet approaches a ‘mini-Neptune’, suffering gravitational tugs that deform it and heat its interior, possibly generating volcanic activity
During each orbit, mini-Neptune c and terrestrial planet d pass very close to each other. Each approach produces a gravitational tug of the first on the second, causing its orbit to trace a somewhat elliptical path in which it deforms slightly each time it revolves around the star.
These deformations can create enough internal friction to heat the interior of the planet and produce volcanic activity, a phenomenon similar to what the planet Jupiter exerts on its satellite Io, which holds the record for volcanic activity in the entire solar system.
Planet d lies at the inner edge of the habitable zone, the region around a star where pressure and temperature conditions would allow liquid water to exist on a planet’s surface.
If the newfound planet is as geologically active as the science team suspects, it could support an atmosphere, and temperatures could drop enough on the planet’s nightside for water to condense on the surface.
The night side of the planet could harbor liquid water on its surface
“While the University of Montreal team analyzed observations with the Spitzer Telescope (NASA), our team discovered the signal corresponding to the planet LP791-18d using proprietary planet search software,” said Francisco J. Pozuelos, researcher at the Institute for Astrophysics of Andalusia (IAA-CSIC) who participated in the work.
“While processing data from the TESS space telescope, our algorithm detected the signal, which was not detected, and we began an observation campaign with ground-based telescopes using the SPECULOOS telescope network and coordinating with the other teams involved in the discovery,” he said. he adds.
A big open question in astrobiology, the field that studies the origin of life, is whether tectonic or volcanic activity is necessary for life to arise: In addition to providing an atmosphere, these processes could move materials that would otherwise sink and be destroyed. trapped in the crust, including those considered important for life, such as carbon.
“Planet c has already been approved for observation with the recently launched James Webb Space Telescope, and we believe that planet d is also an excellent candidate for atmospheric studies”, concludes Pozuelos.
Reference:
MS Peterson et al. “An Earth-sized temperate planet with tidal heating transiting an M6 star”. Nature (2023)