In a recent study submitted to The Astrophysical Journal Letters, an international team of researchers led by the University of California, Los Angeles (UCLA) examines the potential for water worlds around M dwarf stars. Water worlds, also known as Ocean worlds are planets that have bodies of liquid water either directly on their surface, like Earth, or somewhere below it, like Jupiter’s moon Europa and Saturn’s moon Enceladus.
For the study, the researchers focused on super-Earths and sub-Neptunes with hydrogen (H)/helium (He) atmospheres for nearby exoplanets orbiting M dwarf stars in an attempt to calculate their total mass of water. So what were the most significant results related to water worlds around M dwarf stars?
“Those planets that contain a significant fraction of their total mass (10-50%) in water may be extremely rare or non-existent,” said Dr James Owen, Senior Lecturer in Exoplanet Physics at Imperial College London and co-author of the studio, recently Universe Today. “This would imply that planet formation is fairly uniform over a wide range of stellar masses, producing the same type of planets: terrestrial worlds that acquired a small percentage by mass of hydrogen gas from the accretion disk around the young star.”
Ultimately, the researchers concluded that while the existence of waterworld populations “remains elusive,” they offered potential avenues for more conclusive results related to waterworld populations. These include looking for the presence of hydrogen and helium around low-mass exoplanets and measuring the age of an exoplanet to better determine its long-term evolution. So what future studies are in the works to get more conclusive results?
“This will come from JWST [James Webb Space Telescope] observations of sub-Neptunes: if the results are consistent with large fractions of the mass of water in their atmosphere (i.e., steamy atmospheres), then it suggests that the planets are indeed worlds.” aquatics,” Dr. James Rogers, who is a postdoctoral fellow at UCLA and lead author of the study, recently told Universe Today. “However, if the atmospheres are consistent with being dominated by H/He, then it suggests that they are not aquatic worlds.”