According to the researchers, water is the most likely candidate. “This is the best evidence yet for the existence of water worlds, a type of planet that astronomers have long theorized to exist.”, explains Björn Benneke, co-author of the study and professor of astrophysics at the University of Montreal, quoted in a press release. The high temperatures of these planets mean that they might be enveloped in a vapor atmosphere, specify the team of researchers, whose study was published Thursday December 15 in the journal Nature astronomy.
“The temperature in Kepler-138d’s atmosphere is likely above the boiling point of water, and we expect a thick, dense vapor-filled atmosphere on this planet.”says Caroline Piaulet, from the Trottier Institute for Research on Exoplanets at the University of Montreal, who led the research. “Under this atmosphere of vapor, to hear itthere might potentially be liquid water at high pressure, or even water in another phase that occurs at high pressure, called supercritical fluid (when the material is subjected to a high temperature but not to the point of becoming solid, editor’s note)”.
