Free Astronomy Magazine July-August 2021

47 JULY-AUGUST 2021 ASTRO PUBLISHING Goddi led a team that used ALMA to study three high- mass, very young stars in a star-forming region called W51, about 17,000 light-years from Earth. They used ALMA when its antennas were spread apart to their far- thest extent, providing resolving power capable of mak- ing images 10 times sharper than previous studies of such objects. They were looking for evidence of the large, stable disks seen orbiting smaller young stars. Such disks propel fast- moving jets of material outward perpendicular to the plane of the disk. “With ALMA’s great resolving power, we expected to fi- nally see a disk. Instead, we found that the feeding zone of these objects looks like a chaotic mess,” said Adam Ginsburg of the University of Florida. The observations showed streamers of gas falling toward the young stars from many different directions. Jets indi- cated that there must be small disks that are yet unseen. In one case, it appears that some event actually flipped a disk about 100 years ago. The researchers concluded that these massive young stars form, at least in their very early stages, by drawing in ma- terial from multiple directions and at unsteady rates, in sharp contrast to the stable inflows seen in smaller stars. The multiple channels of incoming material, the as- tronomers said, probably prevent the formation of the large, steady disks seen around smaller stars. “Such a ‘dis- ordered infall’ model was first proposed based on com- puter simulations, and we now have the first observational evidence supporting that model,” Goddi said. A LMA image of the chaotic scene around some massive young protostars: W51e8 (above), W51e2 (right), W51n (below). Grey shows dust close to the star, while the red and blue indicate material in the jets moving rapidly out- ward from the star. Red shows material moving away from Earth and blue material moving toward Earth. [Goddi, Gins- burg, et al., Sophia Dagnello, NRAO/AUI/NSF] !