A new study has found that gas giants such as Jupiter and Saturn formed by quickly bringing together millions of pebble-sized building blocks to prevent other potential planets from forming in their place.
Stars get born when slowly rotating gas clouds collapse inwards, and protostars spin at increasingly faster speeds at the heart of the gas and dust disk. The dust grains bind with one another over time and form small pebbles, then asteroid-sized planetesimals, then entire planets.
While the exact details of this process are still being debated by astronomers, researchers working on the new study have put together a simulation that informed how the gas giants use small pebbles and quick actions to form in the universe, and why they push so many planets at the outskirts of the solar system.
Harold Levison, lead author on the study and astronomer from the Southwest Research Institute (Colorado), gave a statement to Space.com informing that “This is the first model that we know about that you start out with a pretty simple structure for the solar nebula from which planets form, and end up with the giant-planet system that we see”.
Planet formation was initially believed to rely on the slow evolution from dust, to pebble-sized debris, to asteroid-sized planetesimals, to space objects large enough to collect the nearby hydrogen and helium and transform into gas giants. And yet the theory suggested that gas giant formed quickly, before the gas around the newborn sun even had time to dissipate.
The chances of two (2) or more giant planetesimals colliding with one another and merging together were not high enough to form massive gas giants quickly enough.
Michiel Lambrechts and Anders Johansen, a research duo from Lund University (Sweden), were the first to suggest that gas giants may form quickly due to small pebbles fusing together after forming from dust grains. The theory was proposed back in 2012 and offered an explanation that made the entire gas giant forming process 1000 times faster than what the earlier models suggested.
Levison and his team got inspired by this theory and decided to explore it even further. While field experts knew that there were chunks of matter surrounding young starts, older models suggested that about 100 planetesimals collect the same number of pebbles until they each get to be 10 percent (10%) of the size of our planet.
The problem with this line of thought was that none of the planetesimals were big enough to be the core of the gas giant. So the new model suggests that they vary in size and that the bigger objects knock the smaller objects out of their way.
Katherine Kretke, co-author on the study and astronomer from the Southwest Research Institute (Colorado), gave a statement f her own informing that in the new model, the larger objects have a tendency of scattering the smaller objects can “scatter them back, so the smaller ones end up getting scattered out of the pebble disk”.
She went on to add that this is the equivalent of the bigger guy bullying the smaller guy so that he can be the one to eat all of the pebbles, and continue to get big enough so that he can form the core of the gas giant.