This newly-discovered planet might be a "water world"

Using observations from NASA's TESS space telescope, an international team of astronomers has discovered an exoplanet (a planet outside our solar system) that could be completely covered in water. The extrasolar world, named TOI-1452 b, is orbiting one of two small stars in a binary system located in the Draco constellation about 100 light-years from Earth.

Led by Charles Cadieux, a Ph.D. student at the Université de Montréal and a member of the Institute for Research on Exoplanets (iREx), the team's findings are published in The Astronomical Journal.

The researchers believe it could be an "ocean planet," a planet completely covered by a thick layer of water, similar to some of Jupiter's and Saturn's moons. While the exoplanet is probably rocky like Earth, its radius, mass, and density suggest a world very different from our home planet.

"TOI-1452 b is one of the best candidates for an ocean planet that we have found to date. Its radius and mass suggest a much lower density than what one would expect for a planet that is basically made up of metal and rock, like Earth," Cadieux said in a statement.

The researchers, based on the TESS signal, which showed a slight decrease in brightness every 11 days, predicted a planet about 70% larger than Earth. They then observed the system with SPIRou, an instrument installed on the Canada-France-Hawaii Telescope in Hawai'i to determine its mass, which is believed to be nearly five times that of Earth.

SPIRou operates in the infrared spectrum and is ideal for studying low-mass stars such as TOI-1452.

Analysis of the planet by Mykhaylo Plotnykov and Diana Valencia of the University of Toronto, who are specialists in exoplanet interior modeling, shows that water may make up as much as 30% of its mass, a proportion similar to that of Jupiter's moons Ganymede and Callisto, and Saturn's moons Titan and Enceladus.

The researchers hope to further observe TOI-1452 b with the James Webb Space Telescope as it is perfectly positioned for investigation by the powerful telescope and is one of the few known temperate planets that exhibit characteristics consistent with an ocean planet.

"Our observations with the Webb Telescope will be essential to better understanding TOI-1452 b. As soon as we can, we will book time on Webb to observe this strange and wonderful world," said René Doyon, Université de Montréal Professor and Director of iREx and of the Observatoire du Mont-Mégantic (OMM). Doyon overviewed the conception of Webb's component NIRISS.