NASA | GSFC | STScI | HubbleSite | 2022 Dec 15
A team led by researchers at the University of Montreal has found evidence that two exoplanets orbiting a red dwarf star are "water worlds," where water makes up a large fraction of the entire planet. These worlds, located in a planetary system 218 light-years away in the constellation Lyra, are unlike any planet found in our solar system. ...
Piaulet and colleagues observed exoplanets Kepler-138 c and Kepler-138 d with NASA's Hubble and the retired Spitzer space telescopes and discovered that the planets could be composed largely of water. These two planets and a smaller planetary companion closer to the star, Kepler-138 b, had been discovered previously by NASA's Kepler Space Telescope. The new study found evidence for a fourth planet, too.
Water wasn't directly detected at Kepler-138 c and d, but by comparing the sizes and masses of the planets to models, astronomers conclude that a significant fraction of their volume – up to half of it – should be made of materials that are lighter than rock but heavier than hydrogen or helium (which constitute the bulk of gas giant planets like Jupiter). The most common of these candidate materials is water. ...
Hubble Helps Discover a New Type of Planet Largely Composed of Water
ESA Hubble Science Release | 2022 Dec 15
Astronomers Find That Two Exoplanets May Be Mostly Water
Trottier Institute for Research on Exoplanets | University of Montreal | 2022 Dec 15
Discovery of a New Type of Planet Largely Composed of Water
University of New Mexico | 2022 Dec 15
Evidence for the Volatile-Rich Composition of a 1.5-Earth-Radius Planet ~ Caroline Piaulet et al
- Nature Astronomy (15 Dec 2022) DOI: 10.1038/s41550-022-01835-4 (pdf)