Some astronomers have discovered an exoplanet (planet outside our solar system) similar in size to Earth and which, it seems, is largely covered by volcanoes. The planet, named LP 791-18 d, could experience volcanic eruptions as frequently as Io, a moon of Jupiter, which is the most volcanically active body in our solar system.
These astronomers, led by Merrin Peterson and Björn Benneke of the University of Montreal in Canada, found and studied the planet using data from NASA’s Transiting Exoplanet Survey Satellite (TESS) and the now-retired Spitzer Space Telescope, as well as a set of terrestrial astronomical observatories.
The amount of volcanic activity that exists throughout the planet possibly emits enough gas for the star to have and maintain an atmosphere.
Due to its proximity to its star, the rotation of LP 791-18 d has been synchronized with its translation, which means that one side of the planet is constantly facing its star, while perpetual night reigns on the other side. The dayside is probably too hot for liquid water to exist on the surface. But on the night side it is possible that the water vapor condenses. The latter, together with the possible existence of an atmosphere, makes the night face potentially possess the necessary conditions for life.
Volcanism also contributes to the potential habitability of a region of the planet. Although this is a violent geological activity, capable of killing living things, it also has the ability to transport materials to the surface that would otherwise remain inaccessible deep underground. Some of these materials are essential ingredients for life. This means that the chemical milieu in some parts of the surface of LP 791-18 d may be rich enough to have supported the development of prebiotic chemistry.
Artist’s recreation of the planet LP 791-18 d. (Illustration: NASA’s Goddard Space Flight Center / Chris Smith (KRBwyle))
LP 791-18 d orbits a small red dwarf star about 90 light-years away. The planet is estimated to be only slightly larger and more massive than Earth.
Before the discovery of LP 791-18 d, it was already known of the existence in that solar system of two other worlds, called LP 791-18 by LP 791-18 c. The closest planet to the star, b, is about 20% larger than Earth. The farthest planet, c, is about 2 and a half times the size of Earth and more than seven times its mass.
During each orbit, planets d and c pass very close to each other. Each close pass causes the more massive planet c to produce a considerable gravitational tug on planet d, causing it to temporarily deform a bit, and giving its orbit an elliptical shape. Those deformations can create enough internal friction to substantially heat the planet’s interior and produce volcanic activity on its surface. Jupiter and some of its moons affect Io in a similar way.
Planet d lies at the inner edge of the habitable zone around its star. That zone is the range of distances to a star within which the temperature is neither too high nor too low to prevent the existence of liquid water in some areas of a world’s surface.
The study is titled “A temperate Earth-sized planet with tidal heating transiting an M6 star”. And it has been published in the academic journal Nature. (Fountain: NCYT by Amazings)
