The best place to look for life beyond our solar system is on exoplanets: planets that orbit stars other than the Sun. Specifically, astronomers look for exoplanets in the habitable zone. This is the region around a star in which a planet could have liquid water on its surface. Any closer to the star, water evaporates. Any farther, it freezes. There are still no definitive detections of water on exoplanets in the habitable zone to date, but a recent study presents an exciting candidate.
A team of astronomers re-analyzed existing data for a habitable zone exoplanet called LHS 1140 b, gaining exciting new insights into its composition and its habitability. The scientists compiled measurements from multiple telescopes to estimate the planet’s size and mass with unprecedented precision and calculated LHS 1140 b’s density to determine what it’s made of. Previous studies had suggested the planet was dry, rocky, and dead, but the new analysis showed that LHS 1140 b is not dense enough to be pure rock. Instead, it must have an atmosphere and/or substantial water. Taking it a step further, the team modeled the planet’s climate and found that surface liquid water is highly plausible. A follow-up study presented data from the James Webb Telescope, suggesting the planet may have an Earth-like atmosphere. Together, the recent studies provide compelling evidence that LHS 1140 b is a “water world,” the name given to an emerging class of planets in astronomy that are rocky like Earth, but with several times more water.
Exoplanet science is a burgeoning field that offers humanity a rapidly expanding frontier in the search for life. Robust evidence for life beyond Earth evades us, but LHS 1140 b has recently become the most promising candidate to characterize a potentially habitable planet.
This study was led by Charles Cadieux, an astronomy researcher at the University of Montreal.
Managing Correspondent: Collin Cherubim
Press Article: Nearby exoplanet may be rich in life-giving water, study finds (Space.com)
Original Journal Article: New Mass and Radius Constraints on the LHS 1140 Planets: LHS 1140 b Is either a Temperate Mini-Neptune or a Water World (The Astrophysical Journal Letters)
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