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New exoplanet: Earth-sized world, dubbed LP 791-18 d, is covered in volcanoes

In an intriguing turn of events in space exploration, astronomers have revealed the discovery of an Earth-sized exoplanet, designated LP 791-18 d, potentially veiled in volcanic activity. 

This distant world may witness volcanic eruptions as frequent as those seen on Jupiter’s moon Io, renowned as the most volcanically active body in our solar system.

The discovery was made possible by the relentless work of astronomers who scrutinized data from NASA’s TESS (Transiting Exoplanet Survey Satellite) and the retired Spitzer Space Telescope. To further validate their findings, the team also relied on a host of ground-based observatories.

Merrin Peterson, an alumnus of the Trottier Institute for Research on Exoplanets (iREx) based at the University of Montreal, spearheaded the research. The results of the study were recently published in the journal Nature.

What we know about LP 791-18 d

Björn Benneke, an iREx astronomy professor who was a significant contributor to the research, shed light on the planet’s unique features. 

“LP 791-18 d is tidally locked, which means the same side constantly faces its star,” he explained. “The day side would probably be too hot for liquid water to exist on the surface. But the volcanic activity that we suspect pervades the planet could uphold an atmosphere, which may, in turn, allow water to condense on the night side.”

The exoplanet orbits a petite red dwarf star in the southern constellation Crater, roughly 90 light-years away from us. The team’s estimates suggest that LP 791-18 d is just slightly larger and denser than Earth.

Before this discovery, astronomers had already identified two other planets within the same system, tagged as LP 791-18 b and c. The innermost planet, b, surpasses Earth by about 20% in size. Meanwhile, the outer planet, c, is approximately 2.5 times the size of Earth and boasts more than seven times its mass.

The intriguing dynamics of this system emerge during each orbit. Both planets d and c have a close encounter, during which the heavier planet c exerts a gravitational tug on planet d, resulting in a somewhat elliptical orbit. 

This gravitational dance causes planet d to deform slightly with each orbit, which in turn could generate sufficient internal friction to heat the planet’s core, triggering surface volcanism – a phenomenon akin to the gravitational effects of Jupiter and its moons on Io.

LP 791-18 d lives inside the habitable zone

LP 791-18 d resides on the inner fringe of the habitable zone, the region around a star where scientists theorize the existence of liquid water on a planet’s surface. Assuming the planet exhibits as much geological activity as the researchers suspect, an atmosphere could be sustained. This would allow temperatures to plummet enough on the planet’s dark side for water to condense.

The team already secured observing time for planet c on the James Webb Space Telescope, and they believe planet d presents an equally promising candidate for atmospheric studies.

Jessie Christiansen, a research scientist at NASA’s Exoplanet Science Institute at Caltech, emphasized the implications of these findings. 

“A big question in astrobiology, the field that broadly studies the origins of life on Earth and beyond, is if tectonic or volcanic activity is necessary for life,” she said. “In addition to potentially providing an atmosphere, 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.”

The enduring value of the Spitzer Space Telescope

Finally, these discoveries underscore the enduring value of Spitzer’s mission, despite its decommission in January 2020. 

“It is incredible to read about the continuation of discoveries and publications years beyond Spitzer’s end of mission,” said Joseph Hunt, Spitzer project manager at NASA’s Jet Propulsion Laboratory in Southern California. “That really shows the success of our first-class engineers and scientists. Together they built not only a spacecraft but also a data set that continues to be an asset for the astrophysics community.”

The enduring legacy of the Spitzer Space Telescope is evident in the new findings about LP 791-18 d. The data it collected over its operational lifespan continues to unveil new worlds, fostering a deeper understanding of the universe.

The discovery of LP 791-18 d, a world that might resemble a fiery, volcanic version of our own, stirs up excitement and curiosity in the scientific community. Its unique features and dynamics also open up new questions regarding the conditions required for life to exist.

As our quest for understanding the universe continues, it’s discoveries like these that fuel our collective imagination and deepen our knowledge of the cosmos. 

Undoubtedly, the study of LP 791-18 d and its system will provide invaluable insights into the mechanisms that govern other celestial bodies, perhaps even shedding light on the mysteries of our own planet.

As we await further observations from the James Webb Space Telescope, the scientific community is abuzz with anticipation, eager to unveil more secrets of LP 791-18 d. 

This discovery is not just an achievement in the field of exoplanetary research; it’s a testament to human curiosity and the relentless pursuit of understanding the universe that surrounds us.

More about the hunt for habitable exoplanets

The search for habitable exoplanets — planets that orbit stars outside our solar system — is a hot topic in the field of astronomy and astrobiology. Scientists aim to find worlds that could potentially support life as we know it. 

This primarily involves seeking planets, such as LP 791-18 d, that are not only within the habitable zone, also known as the “Goldilocks zone,” of their respective stars, but also have conditions that could support liquid water – a crucial ingredient for life as we know it.

The Goldilocks zone

To begin, the “Goldilocks zone” is a term used to define the region around a star where the conditions are just right – not too hot, not too cold – for liquid water to exist on a planet’s surface. This zone’s location depends on the star’s size and temperature. For instance, a small, relatively cool star’s habitable zone would be much closer to the star compared to the habitable zone around a larger, hotter star.

In the hunt for these potentially habitable exoplanets, scientists primarily use two methods: the transit method and the radial velocity method.

The transit method involves observing the light coming from a star and looking for periodic dimming. This dimming suggests that a planet is passing in front of the star, blocking some of its light. NASA’s Kepler Space Telescope and TESS (Transiting Exoplanet Survey Satellite) have been remarkably successful in finding exoplanets using this method.

On the other hand, the radial velocity method – also known as Doppler spectroscopy – involves observing the star’s light for periodic shifts in its color. These shifts suggest that a planet is pulling on the star as it orbits, causing the star to move towards and away from us in a regular pattern.

Complexity of determining if life can exist on an exoplanet

While these methods can identify exoplanets and provide some information about their size, orbit, and mass, determining whether these planets are truly habitable is a much more complex task. 

Scientists use computer models to simulate the planets’ potential atmospheres and surface conditions based on their size, distance from their star, and their star’s temperature.

The James Webb Space Telescope will provide even more sophisticated tools for characterizing the atmospheres of exoplanets. It’s expected to detect and analyze the chemical composition of exoplanet atmospheres, offering clues about whether these worlds could support life.

Although LP 791-18 d shows promise being in the “Goldilocks zone,”, no exoplanet has been confirmed as habitable, and the search continues. However, several potentially habitable exoplanets have been found. These include Proxima Centauri b, located in the habitable zone of the nearest star to our solar system, and the seven Earth-sized planets in the TRAPPIST-1 system.

The hunt for habitable exoplanets is not just about finding alien life. It’s also about understanding the conditions that make life possible and how common these conditions might be in the universe. Each discovery brings us one step closer to answering the fundamental question: Are we alone in the universe?

Image Credit: NASA


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