At a distance of 90 l.y. from Earth, around a red dwarf in the constellation Crater, an exoplanet resembling the Jovian moon Io has been discovered.
The discovery of this volcanic world was made possible by the work of a team of researchers led by Merrin Peterson, who directs the Trottier Institute for Exoplanet Research at the University of Montreal. The team painstakingly analyzed data from observations made by the Spitzer Space Telescope, the Transiting Exoplanet Survey Satellite (TESS) and a number of ground-based telescopes.
The particular system of LP 791-18
LP 791-18 is a small cold red dwarf star orbiting in the constellation Crater, 87 l.y. from our planet. This star is known in the astronomical world for its very small size and its ability to host up to three planets.
LP 791-18b is the innermost planet in this planetary system and is a super-Earth, slightly larger than our planet, while the outermost, LP 791-18c, is a mini-Neptune, a possibly gaseous planet with a mass 7 times that of the Earth. Between these two planets is the main character of this incredible discovery: LP 791-18d.
LP 791-18d: The perfect copy of galileian moon Io
LP 791-18d is an Earth-like planet orbiting so close to its parent star that it is tidally locked to the star, always orbiting the same hemisphere. Despite its proximity to the star, the planet could potentially be habitable, as it falls perfectly within the habitable zone of the planetary system. How is this possible? The answer is simple: the terminator!
The term “terminator” is used to define the area of a planet that straddles the day and night hemispheres. It is precisely this area of the planet that is the prime candidate for hosting life forms, although the surprises do not end there!
LP 791-18d is indeed a very peculiar planet: its surface is completely covered with volcanic cones from which glowing lava flows. In fact, the planet, which orbits very close to its own star, is perturbed by its star’s gravitational pull, causing internal heating and the release of glowing molten rock from the surface. Because of this peculiarity, LP 791-18d was immediately compared to Io, Jupiter’s innermost moon in the small Jovian system.
Although the planet is entirely covered by volcanic cones, the high temperature of the day side could cause some of the water to condense and fall back to the surface as rain in the night hemisphere.
LP 791-18 system in the near future
LP 791-18 is certainly a very interesting planetary system to study. As a result of this discovery, NASA has announced that the James Webb Space Telescope will be used to photograph and study this system in the future, with much of the study time apparently devoted to LP 791-18d.