UdeM researchers confirm a fifth potentially habitable planet around L 98-59

Summary

A team led by the Trottier Institute for Research on Exoplanets (IREx) at the Université de Montréal has achieved the most precise study to date of the L 98-59 planetary system, and confirmed the existence of a fifth planet in the star’s habitable zone, where conditions could allow liquid water to exist. Volcanic planets, a sub-Earth, and a water world Charles Cadieux, the IREx researcher who led the study on the L 98-59 system. Courtesy photo Credit: Courtesy L 98-59, a small red dwarf located just 35 light-years from Earth, hosts three small transiting exoplanets discovered in 2019, thanks to NASA's TESS space telescope, and a fourth planet revealed through radial velocity measurements with the European Southern Observatory's ESPRESSO spectrograph. All four planets orbit their parent star in a compact orbital configuration, all at distances five times closer than Mercury is to the Sun. By carefully reanalyzing a rich set of observations from ground-based and space-based telescopes, a team led by Université de Montréal and Trottier Institute for Research on Exoplanets (IREx) researcher Charles Cadieux has determined the planets’ sizes and masses with unprecedented precision. “These new results paint the most complete picture we’ve ever had of the fascinating L 98-59 system,” said Cadieux. “It’s a powerful demonstration of what we can achieve by combining data from space telescopes and high-precision instruments on Earth, and it gives us key targets for future atmospheric studies with the James Webb Space Telescope [JWST].” All planets in the system have masses and sizes compatible with the terrestrial regime. The innermost planet, L 98-59 b, is only 84% of Earth’s size and about half its mass, making it one of the rare sub-Earths known with well-measured parameters. The two inner planets may experience extreme volcanic activity due to tidal heating, similar to Jupiter’s volcanic Moon, Io, in the Solar System. Meanwhile, the third, unusually low in density, may be a...