Folks studying planetary formation have been struggling with just about everything. Back before we had good data, some models suggested that planets might form in a few hundred thousand years once the process got started, and then we started seeing disks around stars that are one to three million years old, and things looked good for forming planets until we realized those disks don’t have enough stuff to form planets. So what’s going on?
It turns out that that the disks we’ve been looking at are likely post-planet formation and are, in many cases, only showing us what is left behind. In a new paper in Astronomy & Astrophysics, a team of Dutch observers describes new observations of protostars (still forming) in the Perseus Molecular Cloud, and they found that the conditions in these exceedingly young systems are perfect for planet formation. This means that before a star fully settles into nuclear burning, it already may have planets surrounding it. So yes, planets can form in a few hundred thousand years, and it is in the first few hundred thousand years that formation takes place.