Using NASA's Transiting Exoplanet Survey Satellite (TESS) and the now-retired Spitzer Space Telescope, scientists discovered a fascinating volcanic exoplanet called LP 791-18d. Distinguished by its relentless volcanic activity and a stark contrast between its perpetually light and dark hemispheres, this fascinating celestial body opens new avenues of research.
Artist impression of a volcanic exoplanet - (Image Credit: Diego Barucco via Shutterstock / HDR tune by Universal-Sci)
Volcanic activity in our own solar system
Researchers have uncovered signs of past volcanic activity all through the solar system, on every terrestrial planet, numerous moons, and even a handful of asteroids!
However, there's a lot less going on when it comes to active volcanoes. It's known that Earth's volcanoes are still brimming with activity, and there's a possibility that Venus' volcanoes are similarly active.
In terms of sheer volcanic fervour, Jupiter's moon Io surpasses all, claiming the title of the most volcanically active world in our solar system.
The newly discovered exoplanet, LP 791-18d, would increase the number of known volcanically active planets to three.
LP 791-18d, a genuinely fascinating world.
To paint a picture for LP 791-18d, imagine a planet the size of Earth but profoundly different. One hemisphere basks in eternal daylight, the other is cloaked in endless night, and a multitude of active volcanoes blanket the surface.
Located approximately 90 light years away, LP 791-18d orbits a small red dwarf star. The presence of volcanic activity on this world makes it particularly intriguing for astronomers, as volcanism promotes an interplay between a planet's interior and its exterior.
Stephen Kane, an astrophysicist at UC Riverside, explained in a press release that volcanism plays a crucial role in creating a planetary atmosphere, which in turn can enable the existence of surface liquid water, a necessary component for life as we know it.
Planetary Neighbors
In the same star system as LP 791-18d, astronomers had previously discovered two other planets, named LP 791-18b and c. The outermost planet, LP 791-18c, is nearly nine times the mass of Earth and about 2.5 times its size.
During their orbits, planets LP 791-18c and LP 791-18d come remarkably close to one another. The substantial size of planet c exerts a gravitational pull on planet d, distorting its orbit from a perfect circle into an ellipse. This alteration causes friction, heating the interior of the planet and generating surface volcanic activity.
Tidally locked
Another peculiar aspect of LP 791-18d is its lack of rotation.
"LP 791-18d is tidally locked, meaning one side perpetually faces its star," said Björn Benneke, co-author of the paper and astronomy professor at the Trottier Institute for Research on Exoplanets, based at the University of Montreal.
"The day side may be too hot for liquid water to exist on the surface. However, the expected ubiquitous volcanic activity could sustain an atmosphere, potentially allowing water to condense on the cooler night side," added Benneke.
Artist impression of LP 791-18 d itself. The blue dot in the background is LP 791-18c, a larger neighbouring planet whose gravitational pull may be at the root of the volcanic activity.
Image Credit: NASA’s Goddard Space Flight Center/Chris Smith (KRBwyle)
The Impact of Volcanic Activity on Atmospheres and potential life
Despite the constant volcanic eruptions likely rendering the planet inhospitable, the volcanoes provide valuable insights into planetary evolution.
"Understanding whether tectonic or volcanic activity is essential for life is a major question in astrobiology, the study of life's origins on Earth and beyond," noted Jessie Christiansen, co-author of the paper and research scientist at the California Institute of Technology.
"These processes may not only supply an atmosphere but could also stir up substances that might otherwise be buried in the crust, including essential elements for life, like carbon," said Christiansen.
Recent discoveries of active volcanoes on Venus suggest that Earth-sized planets can still contribute to their atmospheres, irrespective of plate tectonics.
Volcanic emissions mainly consist of carbon dioxide and water vapor, greenhouse gases that can contribute to a planet's warming. "On Venus, volcanic carbon dioxide remained in the atmosphere, propelling the planet into a runaway greenhouse state," Kane explained.
"Presently, Venus has surface temperatures exceeding 850 degrees Fahrenheit, similar to a wood-burning pizza oven, making the prospect of life slim. However, it might not have always been this extreme," he continued.
Volcanoes could be a significant factor in understanding Venus's history. Planets like LP 791-18d offer vital clues on how volcanic activity shapes a planet's environment over time, enriching our understanding of both Venus and Earth.
If you are interested in more details about the research, be sure to check out the paper published in the peer-reviewed scientific journal Nature, listed below this article.
Sources and further reading:
A temperate Earth-sized planet with tidal heating transiting an M6 star (Nature)
Evidence that Venus is volcanically active (University of Alaska Fairbanks)
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