New earth-sized planet discovered, covered in volcanoes

A remarkable discovery has been made by astronomers regarding an Earth-sized planet named LP 791-18d, located approximately 90 light years away. This planet, orbiting a small red dwarf star, presents a truly unique environment. Half of its surface is perpetually bathed in daylight, while the other half remains shrouded in eternal darkness. Furthermore, LP 791-18d is characterized by an extensive array of active volcanoes, which has piqued the interest of scientists.

Volcanism holds great significance due to its role in facilitating interactions between a planet’s interior and exterior. UC Riverside astrophysicist Stephen Kane explained that volcanism plays a crucial part in the development of a planetary atmosphere, which in turn enables the presence of surface liquid water—an essential requirement for sustaining life as we currently understand it.

LP 791-18d joins two other known planets within the same star system, LP 791-18b and LP 791-18c. The outer planet, LP 791-18c, boasts a size 2.5 times that of Earth and a mass nearly nine times greater. As these two planets orbit their star, they come into close proximity with each other, resulting in the gravitational pull of LP 791-18c affecting the orbit of LP 791-18d. This gravitational interaction causes LP 791-18d’s orbit to become more elliptical, generating friction that heats the planet’s interior and leads to surface volcanic activity.

The discovery of LP 791-18d was made using data gathered from NASA’s Transiting Exoplanet Survey Satellite (TESS) and the now-retired Spitzer Space Telescope. Stephen Kane, who was involved in the TESS observations, co-authored a paper on the newly found planet published in the scientific journal Nature.

One prominent characteristic of LP 791-18d, highlighted in the research paper, is its lack of rotation. Björn Benneke, corresponding co-author and astronomy professor at the Trottier Institute for Research on Exoplanets, University of Montreal, explained that LP 791-18d is tidally locked, with one side perpetually facing its star. This means that the daytime side of the planet would likely be too hot to support liquid water on the surface. However, due to the extensive volcanic activity believed to occur across LP 791-18d, an atmosphere could potentially form, allowing water to condense on the cooler nighttime side of the planet.

Although the presence of numerous continuously erupting volcanoes would render LP 791-18d uninhabitable, their existence provides valuable insights into planetary evolution. Jessie Christiansen, a co-author of the paper and research scientist at the California Institute of Technology, noted that a significant question in astrobiology is whether tectonic or volcanic activity is necessary for life. These processes, apart from potentially creating an atmosphere, can bring up materials that would otherwise sink and become trapped in the planet’s crust, including carbon—a vital element for life.

The recent discovery of active volcanoes on Venus has also shown that planets similar in size to Earth can continue to accumulate atmospheric components, regardless of the presence of plate tectonics. Volcanic emissions primarily consist of carbon dioxide and water vapor, both greenhouse gases that contribute to the retention of heat. Stephen Kane mentioned that on Venus, volcanic carbon dioxide remained in the atmosphere, resulting in a runaway greenhouse effect that elevated surface temperatures to over 850 degrees Fahrenheit, rendering the likelihood of life there slim. However, this might not have always been the case. Kane suggests that volcanoes hold a significant role in unraveling the mysteries of Venus and understanding how they shape planetary environments over time, including those of Earth and LP 791-18d.

Source: University of California – Riverside

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