May 17, 2023
Astronomers have recently made an exciting discovery in the vast expanse of space - the detection of an Earth-size exoplanet known as LP 791-18 d. This remarkable planet, located beyond our solar system, appears to be covered in a carpet of volcanoes, making it a celestial body of great interest. In fact, LP 791-18 d might experience volcanic outbursts as frequently as Io, one of Jupiter's moons, which is renowned for its intense volcanic activity.
The search for LP 791-18 d involved a comprehensive analysis of data collected from various sources, including NASA's Transiting Exoplanet Survey Satellite (TESS) and retired Spitzer Space Telescope. Additionally, ground-based observatories contributed to the extensive study. The findings of this groundbreaking research have been published in the prestigious scientific journal Nature, with Merrin Peterson, a graduate of the Trottier Institute for Research on Exoplanets (iREx) at the University of Montreal, leading the paper.
One intriguing aspect of LP 791-18 d is its tidal locking, which means that the same side of the planet perpetually faces its star. Consequently, the daylight side of the exoplanet is expected to be too hot for liquid water to exist on its surface. However, the planet's widespread volcanic activity is believed to generate sufficient heat to sustain an atmosphere. This unique characteristic could potentially allow water to condense on the night side of LP 791-18 d, offering an intriguing environment for further investigation.
LP 791-18 d orbits a small red dwarf star situated approximately 90 light-years away within the southern constellation Crater. Scientists estimate that the exoplanet is only marginally larger and more massive than Earth, making it an exciting subject for further exploration. Notably, the discovery of LP 791-18 d builds upon existing knowledge of the system, which already included two known planets: LP 791-18 b and LP 791-18 c. LP 791-18 b, the innermost planet, boasts a size approximately 20% larger than Earth. On the other hand, LP 791-18 c, the outer planet, possesses a size over 2.5 times that of Earth and a mass more than seven times greater.
The orbital paths of LP 791-18 d and LP 791-18 c bring them into close proximity during each revolution. The gravitational forces exerted by the more massive planet c cause a slight elliptical deformation in the orbit of planet d. Consequently, these periodic deformations generate substantial internal friction within LP 791-18 d, leading to intense heating of its interior and subsequent volcanic activity at the surface. This phenomenon bears a resemblance to the gravitational influence Jupiter and its moons exert on Io.
Notably, LP 791-18 d resides on the inner edge of the habitable zone, which refers to the range of distances from a star where the presence of liquid water on a planet's surface is theoretically plausible. The scientific team believes that if the planet is indeed as geologically active as they suspect, it could maintain an atmosphere. Furthermore, the temperatures on LP 791-18 d's night side may decrease significantly, creating conditions suitable for water to condense on the surface.
The potential for atmospheric studies on LP 791-18 d has captured the attention of scientists, leading to its selection as an exceptional candidate for observation by the highly anticipated James Webb Space Telescope. The telescope has already been approved to observe LP 791-18 c, further emphasizing the scientific significance of this newly discovered planet. Atmospheric investigations could provide valuable insights into astrobiology, a field focused on the origins of life on origins of life on Earth and beyond.