http://arstechnica.com/science/2014/11/the-early-solar-systems-magnetic-field-sped-planet-formation/
Ars Technica said:One aspect of planetary formation has remained enigmatic. Observations of young star systems indicate that it usually takes less than five million years for the star’s planets to form—perhaps much less. For that to happen, there must be a really efficient mechanism to bring mass into the protoplanetary disk in which the planets form. Gravity alone doesn’t account for it happening so quickly.
Theoretical explanations abound for the fast accretion of material, some of which involve its interactions with a solar system's magnetic field. Until now, there’s been no way to test these models or determine the role of a magnetic field. By examining a meteorite, however, researchers found indications that the magnetic field in the early Solar System was sufficient to account for the short accretion time.