Planets in the making

Our Solar System formed out of a huge, primordial cloud of gas and dust. The vast majority of that cloud formed the Sun, while the leftover disc of rotating material around it eventually coalesced into the orbiting planets we know — and live on — today.

Astronomers can observe similar processes happening around other stars in the cosmos. This splendid Picture of the Week shows a disc of rotating, leftover material surrounding the young star HD 163296. Using the observing power of the Atacama Large Millimeter/submillimeter Array (ALMA) in Chile, astronomers have been able to discern specific features in the disc, including concentric rings of material surrounding the central star. They were even able to use ALMA to obtain high-resolution measurements of the gas and dust constituents of the disc. With these data they could infer key details of the formation history of this young stellar system.

The three gaps between the rings are likely due to a depletion of dust and in the middle and outer gaps astronomers also found a lower level of gas. The depletion of both dust and gas suggests the presence of newly formed planets, each around the mass of Saturn, carving out these gaps on their brand new orbits.