Various factors, such as the initial conditions of the star and the amount of rotation of the system, likely affect where the material accretes. For example, if there is a small amount of rotation in the young star, more material would likely be accreted on to the star and fewer planets would form in the system, Hartigan explains. Meanwhile, other scientists have been hard at work on other pieces of this puzzle. For one, astrophysicist Alan P. Boss of Carnegie Institution's Department of Terrestrial Magnetism has developed a model that describes the dominant thermodynamic processes functioning in the disk. And the distance depends only weakly on the mass of the central star.
Astronomers generally believe that Jupiter's core was formed by the accumulation of icy volatiles.
When the early planet's mass was great enough, it captured gas from the disk of the central star to form the outer layers of the planet. But Boss' model has revealed that such a radius is not in free space about the star, because the formation of the planet occurs inside the dense disk. Or, if there is another Jupiter-sized planet out there, it would have to be found at a distance of about 5 AU from its central star. What's more, Boss' model complements the recent study by Hartigan and his colleagues. Much work remains to figure out how the disk evolves and to resolve the looming conundrums, such as how a Jupiter-sized planet could accrue enough mass fast enough to draw gas particles to its surface before the accretion process ceases.