A new exoplanet discovered orbiting a small red dwarf star about 90 light-years from Earth may be covered in explosive volcanoes.
The exoplanet – named LP 791-18 d – was discovered by NASA’s Spitzer Space Telescope and the Transiting Exoplanet Survey Satellite (TESS). That brings the number of known exoplanets orbiting the star LP 791-18 in the Crater constellation to three – two others are known as b and c.
In terms of size, d is slightly larger than Earth, b would be about 20% larger, c is a super-Earth, with a size of about 2.5 times and seven times the mass of our planet.
It’s a size difference that matters because c and d has very close lanes.
When they come near, c’s superior gravity pulls d’s orbit. This, the researchers say, causes an increase in d’s internal friction, heating its interior and leading to widespread volcanic activity across its surface.
Exoplanets that are like worlds in Star Wars
This may be enough for the planet to sustain an atmosphere, although liquid water on its surface is unlikely.
That is because d is tidally locked, meaning the planet rotates in time with its orbit around the red dwarf – the same principle applies to Earth’s Moon (why we always see the same side).
As such, liquid water is highly unlikely to exist on the star-facing side of d.
“However, the amount of volcanic activity that we suspect occurs across the planet can maintain an atmosphere that can allow water to condense on the night side,” says University of Montreal exoplanet researcher Professor Björn Benneke, who worked on the project.
Volcanic, though potentially a life-friendly world
LP 791-18 d looks promising as a potential candidate for atmospheric studies by the James Webb Space Telescope.
Its volcanic activity could also indicate the presence of plate tectonics like those on Earth.
And which d sitting just inside its star’s habitable zone, there is a small possibility that it may have conditions conducive to some forms of life.
“A big question in astrobiology, the field that largely studies the origins of life on Earth and beyond, is whether tectonic or volcanic activity is necessary for life,” says Dr. Jessie Christiansen, an Australian astrophysicist based at the NASA Exoplanet Science Institute at Caltech, USA.
“In addition to potentially providing an atmosphere, these processes can collect materials that would otherwise sink and become trapped in the crust, including those we think are important for life, like carbon.”
Matthew Ward Agius
Matthew Agius is a science writer for Cosmos Magazine.
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