An artist's illustration depicts exoplanet GJ 9827d (foreground, right) — the smallest exoplanet where atmospheric water vapour has been detected — as it orbits a host star. Two inner planets (bottom left) in the system are also shown. [CNN]
In a revolutionary breakthrough, astronomers wielding the powerful Hubble Space Telescope have detected the presence of water molecules in the atmosphere of GJ 9827d, a scorching exoplanet located 97 light-years away from Earth.
This celestial body, roughly twice the diameter of our home planet, has become the smallest exoplanet on record with confirmed water vapour in its atmosphere, according to a recent study published in The Astrophysical Journal Letters.
The quest for water in space is a crucial element in the search for extraterrestrial life, and GJ 9827d's peculiarities offer valuable insights into the mysteries of planets beyond our solar system. Study coauthor Laura Kreidberg, Managing Director of the Atmospheric Physics of Exoplanets department at the Max Planck Institute for Astronomy, hailed the discovery as a "landmark" and emphasized its proximity to characterizing truly Earth-like worlds. However, the intense heat of GJ 9827d, akin to that of Venus, dampens hopes of finding life on this particular celestial body.
The Hubble Space Telescope, under the leadership of principal investigator Ian Crossfield from the University of Kansas, was specifically designed to unravel the mysteries of GJ 9827d. The observations made during 11 transits over three years, when the planet crossed in front of its host star, provided astronomers with a unique opportunity to scrutinize its atmosphere.
Despite the breakthrough, the true nature of GJ 9827d's atmosphere remains elusive. The researchers are grappling with two intriguing theories. Firstly, the exoplanet might be a mini-Neptune with a hydrogen-rich atmosphere containing water vapour. This theory suggests that GJ 9827d initially formed at a greater distance from its host star, with water present in the form of ice, similar to Neptune and Uranus in our solar system. As the planet migrated closer to its star, intense stellar radiation heated up and potentially caused the escape of hydrogen.
Alternatively, astronomers contemplate a scenario where GJ 9827d could be a warmer counterpart to Jupiter's icy moon Europa, potentially consisting of half water and half rock. This theory opens up possibilities of a complex composition, akin to the intriguing structure of Europa beneath its thick, icy crust.
The search for water in space extends beyond the confines of GJ 9827d, as water is a ubiquitous molecule found across the universe. Thomas Greene, an astrophysicist at NASA's Ames Research Center, highlights that observing water is a gateway to discovering other elements, emphasizing the pivotal role of this discovery in propelling future studies of similar planets by the upcoming James Webb Space Telescope (JWST). With its enhanced infrared observations, the JWST will enable a comprehensive inventory of elements on distant planets, facilitating a deeper understanding of their formation.
The anticipation is palpable as astronomers eagerly await the data from observations made by the Webb telescope on GJ 9827d. Laura Kreidberg expresses the hope that these revelations will finally settle the longstanding question of water worlds beyond our solar system, further enriching our understanding of the vast and diverse cosmic landscape.
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