An international research team has discovered a new planet so young that it has not yet emerged from the belly of matter where it is forming. It is the youngest protoplanet discovered to date. Its location and surrounding matter patterns suggest that an alternative method of planet formation may be at work. This discovery could help explain the history and characteristics of extrasolar planets observed around other stars.
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 accretes gas from the disc, becoming a giant planet. While this model works well for planets in the solar system, it struggles to explain exoplanets that have been discovered around other stars at distances much greater than the orbit of Neptune, the farthest planet in the system. solar.
Rocky cores should not form far from the central star, so core accretion cannot result in the formation of distant planets. One theory holds that the outer planets form near the central star and move outward. But new observations using an extreme adaptive optics system that allows the Subaru telescope to directly image faint objects near brighter stars show what appears to be a protoplanet forming directly from a distance of 93 au: more than three times the distance between the Sun and Neptune.
Analysis of this object, named AB Aur b, shows that a simple pattern of starlight reflected from a disc anomaly cannot reproduce the observations; but neither is a naked planet model. The best-fit models indicate that AB Aur b is such a young protoplanet that it is still forming in a womb of matter in the protoplanetary disk. The spiral structures near the disc correspond to models where a planet forms directly from the gravitational collapse of surrounding matter. This discovery has profound implications for explaining the numerous peripheral exoplanets observed and the overall theoretical model of planet formation.
“This study sheds new light on our understanding of the different ways planets form,” says Thayne Currie, lead author of the discovery paper.
The 8.2-meter Subaru Telescope is located near the summit of Maunakea in Hawai`i, an inactive volcano known for its unparalleled qualities as an astronomy site and its deep personal and cultural significance to many native Hawaiians.
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Materials provided by National Institutes of Natural Sciences. Note: Content may be edited for style and length.