New observations of the dust cloud around a baby star have revealed what appear to be the early stages of the formation of giant planets.

Using the Very Large Telescope and the Atacama Large Millimetre/submillimetre Array, astronomers have detected clumps in the thick material around the star V960 Mon that could gravitationally collapse to form the seeds of planets like Jupiter.

This discovery could help us better understand the formation of these massive worlds, a process shrouded in dust and mystery.

"This discovery is really fascinating as it marks the first detection of clusters around a young star that have the potential to give rise to giant planets," says astronomer Alice Zurlo from the University of Diego Portales in Chile.

According to models, there are two possible formation pathways for gas giant planets. You start with a baby star surrounded by swirling material left over from the star's formation. Planets are born from these remnants.

The first way is core accretion, which is the same way rocky planets like Earth and Mars form. This is a bottom-up model: clumps of matter stick together and accumulate to form a planet. The other way is top-down, the way stars form: a denser clump in a dense cloud collapses under gravity to form a baby planet. This is the gravitational instability model.

Both scenarios are plausible, so astronomers have looked for signs in the material around baby stars that offer clues about the early stages. And recent technological and analytical advances have made it much more possible than before to discover subtle changes in distant dusty material.

V960 Mon is a young star estimated to be 7,120 light-years away in the constellation Monoceros the Unicorn. It is so young that it was caught shining brightly - an event scientists interpret as an accretion event, when material from the cloud falls on the still-growing star.

Observations using the VLT's optical and near-infrared SPHERE instrument two years after the 2014 outburst, when the star grew to 20 times its previous brightness, revealed strange structures in the material around V960 Mon, like the spiral arms of galaxies. This prompted a group of scientists led by astronomer Philipp Weber from the University of Santiago in Chile to rush to see what they could find in the radio data from ALMA.

ALMA data revealed that the disc of matter around V960 Mon is undergoing a process called fragmentation, an important part of the gravitational instability model. The disc is breaking up into clumps that turn into planet seeds. And indeed, the team found clumps in the spiral arms around V960 Mon, each several times the mass of Earth.

"Until now, no one had ever seen a real observation of gravitational instability taking place on planetary scales," says Weber.

Future studies of current and future telescopes will attempt to study other such exploding young stars in the hope of uncovering more evidence of disc fragmentation and gravitational instability in planet formation.

"We have been looking for these clusters with ALMA for over a decade, because theories of planet formation predict their existence for the creation of massive planets," says astronomer Sebastián Pérez of the University of Santiago in Chile.

"Our discovery could establish direct links between the formation of stars and planets."

 

Source: https://www.sciencealert.com/