How does a planet’s size influence its orbit around its parent star? This is what a recent study published in the Proceedings of the National Academy of Sciences hopes to address as a team of researchers from the University of California, Los Angeles (UCLA) investigated a correlation between planet size and its orbital shape. This study has the potential to help scientists better understand the formation and evolution of exoplanets throughout the cosmos and what this could mean for finding life beyond Earth.
For the study, the researchers analyzed data from NASA’s now-retired Kepler Space Telescope regarding the orbital shapes, also known as eccentricities, on 1,646 exoplanets whose sizes range between 0.5 to 16 Earth-radii. For context, Neptune is 3.88 Earth-radii, Uranus is 4 Earth-radii, Saturn is 9.14 Earth-radii, and Jupiter is 11.2 Earth-radii. In the end, the researchers determined that exoplanets whose radii are between 4 to 16 Earth-radii have eccentricities four times greater than exoplanets whose radii are between 0.5 to 4 Earth-radii.
“Small planets are common; large planets are rare. Large planets need metal-rich stars in order to form; small planets do not. Small planets have low eccentricities, and large planets have large eccentricities,” said Dr. Gregory Gilbert, who is a postdoctoral researcher at UCLA and lead author of the study. “To see a transition in the eccentricities of the orbits at this same point tells us there really is something very different about how these giant planets form versus how small planets like Earth form. That's really the major discovery to come out of this paper.”
What new connections between planetary size and orbital shape will researchers make in the coming years and decades? Only time will tell, and this is why we science!
As always, keep doing science & keep looking up!
Sources: Proceedings of the National Academy of Sciences, EurekAlert!, NASA
Featured Image Credit: NASA/JPL-Caltech
