Exoplanet LP 791-18 d orbits a red dwarf star in the southern constellation Crater that is 90 light-years away from Earth.

An Earth-sized alien world might be dotted with active volcanoes whose emissions could support an atmosphere, according to a recent study.

Exoplanet LP 791-18 d orbits a red dwarf star in the southern constellation Crater that is 90 light-years away from Earth. The research team concluded that it is a little bit bigger and more massive than Earth and that it is also likely much more volcanically active than the planet Earth.

Since LP 791-18 d is tidally locked, only one side ever faces its star. The dayside would be too hot for liquid water to exist on the surface, according to co-author Björn Benneke, an astronomy professor at the University of Montreal’s Institute for Research on Exoplanets, but volcanic activity could support an atmosphere, which may allow water to condense on the nightside.

Using information from NASA’s Transiting Exoplanet Survey Satellite (TESS) and Spitzer Space Telescope, the research team discovered and characterised the Earth-sized alien world, LP 791-18 d.

TESS is actively searching for exoplanets from Earth orbit, looking for the distinctive brightness dips that occur when these planets pass in front of the faces of their host stars.

The LP 791-18 d observations were some of the last ones the infrared-optimized telescope took before it was shut down, according to NASA officials. Spitzer was retired in January 2020. (Spitzer isn’t necessarily finished, though; a private team has suggested reviving the telescope, which was shut down primarily to free up resources for NASA’s James Webb Space Telescope.)

Along with LP 791-18 b and c, LP 791-18 d is the third planet discovered in this star system. Planet d is 2.5 times wider and at least seven times more massive than planet b, which is 20% larger than Earth.

During their orbits around the red dwarf host star, planets c and d come into close proximity to one another, pulling planet d gravitationally and causing it to have an elliptical orbit. The new exoplanet is affected significantly by these interactions.

Due to internal friction and tidal heating, planet d, one of Jupiter’s four Galilean moons, has the highest rate of volcanic activity in the solar system. Io is the body in the solar system with the most volcanic activity because it is influenced by Jupiter and some of its moons.

Sulfur dioxide dominates the atmosphere of Io, but LP 791-18 d is likely able to retain more of its volcanic gases. It’s possible that the planet’s night side is cool enough to support liquid water.

This does not necessarily mean that planet d is a good candidate to support life as we know it; the planet might be too volatile. However, astrobiologists and scientists who are interested in the formation and evolution of exoplanet atmospheres will find the newly discovered world to be an appealing target.

In the same statement, study co-author Jessie Christiansen of NASA’s Exoplanet Science Institute at the California Institute of Technology in Pasadena said that the question of whether tectonic or volcanic activity is required for life is a major one in astrobiology, the field that broadly studies the origins of life on Earth and beyond.

Christiansen added, “These processes could churn up materials that would otherwise sink down and get trapped in the crust, including those we think are important for life, like carbon, in addition to potentially providing an atmosphere.

The James Webb Space Telescope has approved future observations of LP 791-18 c, and planet d may follow. A new study posted online in Nature suggests that it is marginally bigger and more massive than Earth and likely much more volcanically active than our planet.