This new protoplanet might shed some light on how some massive planets are formed, through "disk invisibility"

How are gas giants formed? Well, one might say, just how all the other planets are formed, when a lot of matter from the protoplanetary disc accumulates at a point to the point its own gravity starts attracting other gases and masses in the disc.

Credit: ESO

But a newly discovered planet, orbiting the star AB Aurigae, might bring up some questions. An upcoming gas giant, 9 times the size of Jupiter, is forming on the outskirts of its star system, where there is less matter. That has led astronomers to rethink how gas giants actually form, as by the position of the planet the core wouldn’t be massive enough to accumulate a blanket of hydrogen and helium.

Thayne Currie, an astrophysicist at Subaru Telescope, with his colleagues published a report in Nature Astronomy about this mysterious world forming.

Currie argues this might be the case due to disk instability, where the disk breaks into planet-size fragments, where the fragments collapse on themselves and form giant planets. “My first reaction was, there’s no way this can be true,” says Thayne Currie.

From the period 2016-to 2020, when Currie and her colleagues were observing AB Aurigae through the Subaru telescope, the data collected through the images, a bright spot was seen next to the star, the protoplanet, named AB Aur b orbiting about 14 billion kilometers to its star.

Planet formation from disk instability was never seen before this point, but now we have what is possibly occurring in the AB Aurigae system. This protoplanet is such a special one because distinguishing planet formation through core accretion or disk instability through images could be really hard, but because AB Aur b is so far from its star but is still growing in size is such a big proof to prove planet formation through disk instability is possible.

And the new James Webb Space telescope could help researchers understand gas giant formation better by studying this star system, as the data collected through Subaru and Hubble telescopes help us better understand the formation of giant planets.