Astrophysicists at the RIKEN Laboratory for the Formation of Stars and Planets have suggested that during the planetary formation process, dust grains may merge with each other much earlier than previously thought. This could force them to rethink traditional theories of planet formation.
Scientists explained that massive planets start out as specks of dust that are too small for the human eye. “Planets like Earth, which are thousands of kilometers across, evolved from submicron particles of interstellar dust — a pretty big leap in scale,” said RIKEN’s Satoshi Ohashi. “We are interested to know how dust grains come together to form objects thousands of kilometers across.”
Planets are born from protoplanetary disks – rotating disks of gas and dust around new stars. Ring-shaped structures have been observed in these discs, and it is believed that over time the rings coalesce into larger structures, eventually leading to the formation of planets. But much about this process remains unknown.
Now Ohashi and his colleagues have explored a possible scenario for the formation of these rings through computer simulations. Their results showed that dust can collect into larger particles during the protostar stage, while the star itself is still forming, and much earlier than modern theories of the formation of cosmic objects predict. “We found that ring structures were formed even in the early stages of disc formation,” Ohashi notes. “This suggests that the dust grains may get larger earlier than we previously thought.”
This is an unexpected conclusion, since at the protostellar stage, the dust disk is still in a state of flux – this is hardly a promising place for dust agglomeration. However, the team found similarities between the simulations and observations of 23 ring structures in disks with the ALMA device in Chile and other telescopes.
In the future, the team hopes to capture images of ring structures around protoplanetary disks at multiple wavelengths. This will allow them to compare simulations with observations in more detail.