One major aspect that scientists consider in habitability is the presence of water. When looking for other worlds which might host life, water is a good place to start. Now, a study suggests that exoplanets with water may be more common than previously thought, with many planets likely being formed up of half water and half rock.
Researchers at the University of Chicago examined a group of known exoplanets orbiting around M-dwarf stars, which are the most common type of stars in our galaxy. Dozens of these exoplanets have been discovered through two different techniques: the transit method, where a planet passes in front of a star and causes a spike in its brightness, and the radial velocity method, where a planets gravity causes a very slight change to a stars movements.
In a statement, Enric Palle of the Institute of Astrophysics of the Canary Islands and the University of La Laguna discusses the two different ways to discover planets. When both size and mass are considered together, you can see whether a planet is light and puffy or smaller and dense.
Researchers were surprised to discover that many of them had lower densities, indicating they couldn''t be made entirely of rock. Many of them seemed to be roughly half rock, and half water.
I was horrified when I saw this analysis, and a lot of people in the field assumed these were all dry, rocky planets, according to exoplanet scientist Jacob Bean of the University of Chicago, who will be conducting future research into this topic.
Despite the evidence revealing greater watery worlds than we believed, this doesnt mean that all these planets have liquid water on their surfaces. With many of the planets orbiting close to their stars, it is more probable that their water would be beneath the surface like the subsurface oceans that Jupiters moons Europa, Callisto, Ganymede, and Io.
This possibility may even elicit theories on how exoplanets form, as it could be evidence that planets form further away from their stars where temperatures are lower and ice can form more easily, before migrating intowards.
According to a leading researcher, there was no evidence for so many water worlds orbiting the most common type of star in the galaxy. It has huge implications for the creation of habitable planets.
The findings are published in the journal Science.