An international team of researchers has discovered a new planet so young that it has not yet emerged from the “womb” of matter where it is being formed; it is the youngest protoplanet discovered to date.
This Jupiter-like exoplanet – called AB Aurigae b – is forming at a great distance from its star (equivalent to 93 times the average distance between Earth and our Sun); its description is published in the journal Nature Astronomy.
According to scientists, its location and the patterns of matter around it suggest that an alternative method of planet formation may be at work.
Specifically, the finding supports the idea that giant planets can form from large chunks of gas collapsing through gravitational instability, rather than just the standard model used to explain Jupiter’s formation: the accumulation of nucleus.
In the standard model of planet formation, a large gaseous Jupiter-like planet begins as a rocky core in a protoplanetary disk around a young star.
This core then accumulates gas from the disk and becomes a giant planet.
Although this model works well for planets in the Solar System, it has trouble explaining exoplanets that have been discovered around other stars at distances much greater than the orbit of Neptune, the outermost planet in the Solar System.
The gas giant planets of the Solar System, Jupiter and Saturn, orbit at a distance of between 5 and 10 astronomical units (au) from the Sun, one au being the average distance between the Earth and the Sun.
However, a small minority of giant exoplanets have been imaged at distances of 50 to 200 au from their stars. These exoplanets are suggested to have been created through a process known as disk or gravitational instability.
The researchers observed the formation of AB Aurigae b using the Subaru Telescope in Japan and the Hubble Space Telescope.
The team estimates its mass to be nine times that of Jupiter and suggests that several planets could be orbiting the host star.
“This study sheds new light on our understanding of the different ways planets form,” summarizes Thayne Currie, lead author of the paper.