Astronomers are nonetheless scratching their heads over the inhabitants of exoplanets within the ocean world
In a recent study submitted to The Astrophysical Journal Letters, an international team of researchers led by the University of California, Los Angeles (UCLA) explores 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, like Jupiter’s moon Europa and Saturn’s moon Enceladus.
For the study, researchers focused on super-Earths and sub-Neptunes with hydrogen (H)/helium (He) atmospheres for nearby exoplanets orbiting M dwarf stars to calculate their total water mass. So what were the key findings regarding water worlds around M dwarf stars?
“These planets, which contain a significant portion of their total mass (10-50%) from water, could exist extremely rarely or not at all,” says Dr. James Owen, Senior Lecturer in Exoplanet Physics at Imperial College London and co-author of the study, recently told Universe Today. “This would mean that planet formation is fairly uniform over a wide range of stellar masses, producing the same type of planets: terrestrial worlds that have ingested a few mass percent of hydrogen gas from the accretion disk around the young star.”
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Ultimately, the researchers concluded that while the existence of aquatic world populations “remains elusive,” they offer possible avenues to arrive at more conclusive results regarding aquatic world populations. These include looking for the presence of hydrogen and helium near low-mass exoplanets and measuring an exoplanet’s age to better determine its long-term evolution. So what future studies are in the works to produce more conclusive results?
“That will come from JWST [James Webb Space Telescope] Observations of sub-Neptunes – if the results are consistent with large mass fractions of water in their atmospheres (ie steamy atmospheres), this suggests that the planets are indeed water worlds,” Dr. James Rogers, a UCLA postdoctoral researcher and lead author of the study, told Universe Today. “However, if the atmospheres are consistent with H/He dominance, this suggests they are not aquatic worlds.”
What will we continue to learn about the potential for aquatic worlds in our universe, and will JWST help provide more conclusive results to this study? Only time will tell, and that’s why we know science!
As always, keep doing science and keep looking up!