Hubble finds a new Jupiter-like planet forming in an unusual way: NASA
The newly forming planet captured by Hubble, called AB Aurigae b, is probably around nine times the size of Jupiter and orbits its host star at a distance two times the distance between our Sun and pluto.
The Hubble Space Telescope has photographed a Jupiter-like protoplanet forming through a process that researchers have described as “intense and violent”. According to NASA, this discovery supports a long-debated theory called “disk instability,” which tries to explain how planets similar to Jupiter are formed.
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According to Encyclopedia of Astrobiology, this model is for giant planet formation where a protoplanetary disk becomes dense and cool enough to be unstable to gravitational collapse and thereby resulting in the formation of a gaseous protoplanet. A protoplanetary or circumstellar disc is a disc of gas and dust orbiting a newly formed star, out of which planets are hypothesised to form.
According to the Disk Instability theory, matter slowly moves inwards in this disc as dust particles grow to centimetre-sized pebbles. This is seen as the first step towards the formation of kilometre-sized planetesimals that eventually come together to form planets.
The newly forming planet captured by Hubble is called AB Aurigae b and embedded in a protoplanetary disk with distinct spiral structures swirling around and surrounding a young star that is estimated to be about 2 million years old. That is also about the same age our solar system was when planet formation was underway.
This protoplanet is probably around nine times the size of Jupiter and orbits its host star at a distance of 8.6 billion miles, over two times the distance between our Sun and pluto.
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This has led researchers to conclude that disk instability is what enabled this planet to form at such a great distance from its host star. The observations are also in striking contrast to the expectation of planet formation by the widely accepted core accretion model.
“Nature is clever; it can produce planets in a range of different ways,” said Thayne Currie of the Subaru Telescope and Eureka Scientific, lead researcher on the study, in a press statement.
“Interpreting this system is extremely challenging. This is one of the reasons why we needed Hubble for this project – a clean image to better separate the light from the disk and any planet. We could not detect this motion on the order of a year or two years. Hubble provided a time baseline, combined with Subaru data, of 13 years, which was sufficient to be able to detect orbital motion,” added Currie.
According to NASA, nature itself provided a helping hand to the discovery since the vast disk of dust and gas swirling around the star AB Aurigae is tilted nearly face-on to our view from earth. This new discovery presents strong evidence that some gas giant planets can form by the disk instability mechanism.
This discovery also paves the way for future studies into the chemical composition of protoplanetary discs like AB Aurigae b.
Hubble découvre une planète se formant de manière non conventionnelle
https://indianexpress.com/article/technology/science/hubble-photographs-planet-nine-times-larger-than-jupiter-forming-in-an-unusual-way-7857908/