The Earth-sized planet, named LP 791-18d, sit on the inner edge of the habitable zone of red dwarf star about 90 light years away.
Astronomers from the University of Montreal and around the globe have discovered a new exoplanet whose volcano-carpeted surface could potentially support life — or even spark it.
Their paper, published Wednesday in the journal Nature, described a roughly Earth-sized, temperate planet orbiting a small red dwarf star about 90 light years away, in a southern constellation called Crater.
Named LP 791-18d, the exoplanet (a planet outside our solar system) is only slightly larger than Earth and believed to be covered with volcanoes — a potentially vital step in creating an atmosphere and producing the building blocks of life, the researchers say.
“For the first time, we have an exoplanet (with) a very strong indication that there is volcanic activity,” said Björn Benneke, an astronomy professor at the University of Montreal who planned and supervised the study.
“It gives us an opportunity to understand Earth and Venus and other rocky planets in general (in a different way) than we previously have,” he told the Star.
LP 791-18d is tidally locked, Benneke said — unlike Earth, it doesn’t rotate on its axis, creating a day-night cycle. Instead, one side is constantly exposed to the sun while the other is perpetually dark, leading to a dramatic shift in temperatures.
The planet sits on the inner edge of its star system’s habitable zone, where temperatures are believed to be just right for liquid water to exist on a planet’s surface. Averaging out its temperatures, LP 791-18d’s just a little warmer than Earth, Benneke said.
Although the planet’s day side may be too hot for liquid water, Benneke said its night side could be cool enough for water to condense on its surface and even form glaciers. In between the extremes, he says there exists a middle ground with temperatures similar to Earth.
This intersection “may look something a bit like Iceland,” Benneke said. “You (might) have lots of ice, but also volcanic activity underneath.”
The newly-discovered planet’s volcanoes are believed to stem from its wonky orbit around its star, resulting in a gravitational “tug of war” that cooks the planet from the inside out.
Normally, stars force their planets into a circular orbit. In LP 791-18d’s case, however, another, massive planet — one more than double Earth’s size with over seven times its mass — happens to orbit very close by, Benneke said.
The gravity of the massive body turns LP 791-18d’s orbit elliptical each time it passes by, and each time the pull of its star tries to restore it. This constant pulling slightly deforms the planet, generating great internal friction and significantly heating the planet’s core.
“That heat has to go somewhere,” Benneke said, explaining it often vents through the surface, causing volcanic eruptions. Jupiter’s moon Io, the most volcanically active body in our solar system, operates in a similar way.
While seeming scary, the researchers say volcanoes may actually hold the key to the planet forming a livable atmosphere — and perhaps even life.
An atmosphere may be vital for life, but exoplanets often lose theirs over time, often to high energy radiation let off from their stars, Benneke said. However, as a result of LP 791-18d’s volcanic eruptions letting off great plumes of gas, its atmosphere is constantly replenished, he continued.
“So in some way, the same ideas that apply for the Earth, that life may have started under the water by volcanic activity — that could potentially apply here as well,” Benneke continued.
Co-author Jessie Christiansen, a research scientist at NASA’s Exoplanet Science Institute, explained in a release that tectonic or volcanic activity is suspected to be necessary for life.
“In addition to potentially providing an atmosphere, these (volcanic) 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,” Christiansen said.
Karen Collins, another collaborator and an astronomer at the Center for Astrophysics, said in a different statement that “This discovery is just a first step … Future discoveries will help us understand how the ingredients of life might have come to be on worlds other than our own.”
