The model, presented today at a meeting of the American Astronomical Society, tracks how the gas in molecular clouds compresses to form stars. Simulations predict that these clouds become increasingly turbulent and develop structures like those observed around protostars—evidence of the complex motions of newborn stars and the disks that encase them.
These simulations also reveal how turbulent gas shapes disks by distributing micron-sized dust grains into the thin, dusty rings commonly observed in planet-forming disks.
"Turbulence plays an important role in mixing the rocky building blocks of planets throughout the disk," said Zachary Hafen, a postdoctoral researcher in the astronomy department at the University of Texas at Austin. "This explains why sibling stars tend to host planets with the same composition, even if they formed in different parts of the same disk."
The formation of stars is a complex process. Molecular clouds in space collapse over millions to billions of years, forming smaller and denser clumps of gas and dust. Inside these clumps, turbulent motions create pockets of compressed gas that can reach conditions suitable for star formation. In the dense, inner regions, the gas collapses under its own gravity and forms a protostar—the seeds of future stars. Meanwhile, the remaining gas encircles the protostar and forms a circumstellar disk that is the birthplace of planets.
Scientists have yet to observe and understand exactly how gas clouds collapse to form stars. But astronomers have made tremendous strides in understanding what shapes the properties of those stars and their natal disks. They know, for example, that newborn stars are incredibly fast rotators, with surface speeds sometimes exceeding 100 kilometers, or 62 miles, per second.
Astronomers also learned that the inner edge of the surrounding disks—where planets are expected to form—is remarkably uniform.
"Regardless of the protostar's mass or disk radius, the temperature at the inner disk's edge is nearly the same," Hafen said. "So whatever process sets this temperature must be pretty universal, and we think that process has something to do with turbulence."
