The best way to study planet formation is to observe planets as they form. Astronomers used ALMA to identify the youngest exoplanet ever discovered, hidden in a disk of gas around a newborn star 390 light-years away.
We’ve always wondered how the planets of our solar system formed in the past, and while there are many ways to study planets directly, getting samples of planets, asteroids, and comets, we obviously still can’t see exactly what happened in the past.
The best way to do this is to look beyond the solar system to capture the birth of other exoplanets. University of Florida astronomer Jaehan Bae’s team focused on studying the young star system called AS 209, looking for clues from the protoplanetary disk (the material left over after star formation) around the star that the solar system once had and eventually merged into. 8 planets.
The researchers found that the protoplanetary disk of the AS 209 system has several rings, similar to Saturn’s rings. After analyzing the gaps in the rings and other anomalies, they found the youngest known exoplanet to date, just 1.5 million years old.
However, the study is also strange, because this baby planet is as far as 200 AU from its parent star. In the solar system, Pluto is about 40 AU from the sun, and there are only asteroids, comets and dwarf planets. So how did this young exoplanet form so far away?
While the team’s model explains, for example, that the planet slowly accumulates material until it has enough mass to form a core, the model doesn’t mesh well with the data because the star’s disk of matter is too small for its gravity to be strong enough to initiate planet formation. At the same time, astronomers have seen no evidence that particles clump together and eventually form cores near planets.
Fortunately, the team has enlisted the assistance of the Webb Space Telescope, a powerful telescope that will observe the AS 209 system this month, providing key information to unravel the mystery.
The new paper is published in The Astrophysical Journal Letters.
(Source of the first image: NRAO)
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