Behind the scenes of protostellar disk formation
For a long time the formation of protostellar disks – a prerequisite to the formation of planetary system around stars – has defied theoretical astrophysicists: In a dense, collapsing cloud of gas and dust, the magnetic field would be dragged to the centre as well resulting in a braking effect. Hardly any rotationally supported disk can form this way, unless the tiny grains are removed from the cloud by growing or coagulating into bigger grains. This is the result from a new study published by researchers at the Max Planck Institute for Extraterrestrial Physics and other intuitions. The more realistic simulations now take into account non-ideal magneto-hydrodynamics and ionization chemistry to form a rotationally supported protostellar disk.
|This image shows a colour composite of visible and near-infrared observations of the dark cloud Barnard 68. |
At these wavelengths, the small cloud is completely opaque because of the obscuring effect
of dust particles in its interior [Credit: ESO]
"It is surprising to find that the removal of small dust grains can avoid the 'magnetic braking catastrophe' in disk formation," says Paola Caselli, co-author of the paper. "This is a breakthrough in our understanding of how protoplanetary disks form. At the same time, it demonstrates that chemistry and microphysics are crucial to the fundamental processes in the field of star and planet formation."
Source: Max Planck Society [July 11, 2016]