Astronomers Spot A Baby Gas Giant In The Process Of Forming

The general consensus among modern astronomers is that gas giants are likely created in the protoplanetary disks of gas and dust that appear around newly formed stars. They aren’t quite so sure of what sort of process must take place in order for said formation to occur.

The most commonly held view, called core accretion, is that the process begins when small pieces of matter collide and get stuck together, with the gravity of these bodies attracting more and more material over time. Eventually, there is enough material held together by gravity for a planet to form. The other theory, called disk instability, is that there is a large disk of matter which cools and breaks apart into planet-like chunks, which then develop into planets.

The discovery of AB Aur b is pivotal because it is so far from its star that it is unlikely to have formed by core accretion. It is more likely to have been a fragment from a disk, formed by a “violent and rapid process of gravitational collapse” described by astronomers in this new research.

The research suggests that because “most studies analyze the demographics of imaged, fully-formed planets to constrain planet formation,” current expectations of the canonical core accretion model place said formations inside a range consistent with our own star system. 

AB Aur and the protoplanet AB Aur b show direct evidence that a planet “more massive than Jupiter” can form at a distance that is “in striking contrast to expectations of planet formation by the canonical core accretion model.” At the same time, observations of this newly discovered planet AB Aur b and its sun AB Aur show features that “bear an uncanny resemblance to models of jovian planet formation by disk instability.”

According to lead author Thayne Currie, the study “sheds new light on our understanding of the different ways that planets form.”