Planets may Start Forming Before the Star is Even Finished
Planets form from the accumulation of countless grains of dust swirling around young stars. New computer simulations have found that planets begin forming earlier than previously thought, when a planet’s star hasn’t even finished forming yet.
To make a planet you need to do a lot of gluing, going from tiny grains of dust invisible to the human eye to objects thousands of kilometers across. Prevailing theories of planetary formation assumed that this gluing process begins after a protostar had settled down, but new research is challenging that view.
Satoshi Ohashi and his collaborators at the RIKEN Star and Planet Formation Laboratory used computer simulations to study the evolution of protoplanetary disks around still-forming stars. They found that gaps appeared in the disks much earlier than expected. Those gaps are due to enough dust grains gluing together that their accumulated mass can clear out channels in the disk.
“We found that ring structures emerged even in the early stages of disk formation,” says Ohashi. “This suggests that the dust grains may become bigger earlier than we had previously thought.”
This result is surprising because young protostars are still in a state of significant flux, with their output varying wildly. It’s not exactly the best place for dust grains to quietly glue together.
And yet, observations with the ALMA observatory have revealed gaps in young protoplanetary systems. The simulations performed by Ohashi and his colleagues have shown how those gaps could appear so quickly.