An international team of scientists has discovered planet formation in a star system younger than 500,000 years old.
The find, published today in Nature, is a marked departure from previously accepted theories of planet formation and indicates that stars and planets grow up together like siblings.
The disk lifetime based on a survey of nearby young star clusters is a good deal longer than previously thought.
The researchers looked at only the nearest young star clusters, those within 650 light-years of Earth, and found that the fraction of stars with planet-making disks was higher than previously reported.
She said that the analysis shows that the low-mass stars have longer disk lifetimes. Disks around higher-mass stars are known to disperse faster than this, perhaps because their suns push the gas and dust away faster.
Past studies estimated disk lifetimes by looking at the fraction of young stars of different ages that still have disks. The farther a star cluster is from Earth, the longer the disk lifetime is. Why should a disk’s lifetime depend on how far away it is from us?
The difference between our solar system and those of most red dwarfs may be due to the fact that the disks around the lowest-mass stars have long lifetimes.
The latter doesn’t have gas giants like Jupiter and Saturn, which are about ten times the diameter of Earth.
The stars have many ice giants, like Neptune and Uranus, that are four times the diameter of Earth. It’s possible that Neptune-sized planets arise in larger numbers when a planet-making disk lasts longer, Pfalzner says.
Further reading
S. Pfalzner, S. Dehghani and A. Michel. Most planets might have more than 5 Myr of time to form. arXiv:2210.02420. Posted October 6, 2022.