Birth of a planet spotted by astronomers for only the third time ever

Sighting of new ‘protoplanet’ could give insights into how planets in our own solar system formed

Astronomers have confirmed the very rare discovery of a new planet early in its formation, an advance that could help better understand how gas giants like Jupiter in our own solar system formed.

The sighting of the new “protoplanet”, the stage when a planet is still gathering material from its cosmic surroundings, was confirmed after researchers analysed data from the European Southern Observatory’s Sphere instrument.

To date, only two other protoplanets have been unambiguously identified. They are PDS 70 b and c, both of which orbit the star PDS 70.

The new findings mark only the third time a protoplanet has been discovered by astronomers. They were published by a team including researchers from the University of Liège in Belgium, in the journal Monthly Notices of the Royal Astronomical Society: Letters.

The new study confirmed the existence of the protoplanet in a disk of gas and dust surrounding a star 374 light years from our solar system, called HD 169142.

“We used observations from the Sphere instrument of the European Southern Observatory’s Very Large Telescope (VLT) obtained on the star HD 169142, which was observed several times between 2015 and 2019,” explained study co-author Iain Hammond.

“As we expect planets to be hot when they form, the telescope took infrared images of HD 169142 to look for the thermal signature of their formation,” said the researcher from Australia’s Monash University.

Using this data, scientists could confirm the presence of the protoplanet at about 37 astronomical units, or 37 times the distance from the Earth to the Sun from its star, which is “slightly further than the orbit of Neptune.”

Scientists had earlier in 2019 theorised that a compact source seen in their images could be a protoplanet.

The new findings confirm this hypothesis through a re-analysis of the previous data as well as the inclusion of new observations of better quality.

Researchers revealed the movement of a compact source over time, as expected for a planet orbiting at 37 astronomical units from its star.

They spotted a spiral arm in a disk created by the planet that was visible in its wake.

New images suggest the protoplanet has carved a ring-shaped gap in the disk.

This suggests other protoplanetary disks containing spirals may also harbour yet undiscovered planets, scientists said.

Data also revealed that the planet is buried in dust accreted from the protoplanetary disk, which may also form moons.

“It seems that we have captured it at a younger stage of its formation and evolution, as it is still completely buried in or surrounded by a lot of dust,” said Valentin Christiaens, another study author.

Scientists believe the small number of forming planets found, provide a better understanding of how planets, in particular giant ones like Jupiter, are formed.

They say future observations using Nasa’s James Webb Space Telescope can provide further clues on such early planet formation.