One of the world's biggest radio telescopes has detected the first ever newborn planet, still enveloped in the swirling disc of gas and dust that made it.

Key points:

  • A young planet has been detected in the protoplanetary disc of a distant star for the first time, as it disrupted the flow of gas and dust swirling around the star
  • The distant star is twice the size of our sun, and despite being far from the star the baby planet is already twice the mass of jupiter
  • The new methods will allow more baby planets to be discovered and offer insights in how planets and solar systems are formed
Up until now, scientists have only been able to observe these "protoplanetary discs" by themselves, and then actual planets after the disc has disappeared, said astrophysicist Christophe Pinte from Monash University.
"We have discovered the first proto-planet that is still embedded in its disc around a young star," he said.
So the planet is big, but it's also extremely young — and that is what makes it exciting, said Dr Pinte, lead author of the study published today in Astrophysical Journal Letters.
"There have been lots of discoveries of planets around old stars, but this system is only 4 million years old and it's still in the process of formation."
For comparison: our solar system has been spinning for 4.5 billion years.
It is very, very early days for this alien system and its firstborn planet, which is some 330 light years away from Earth and was discovered in data collected by the Atacama Large Millimetre/submillimetre Array (ALMA) in Chile.

'Kink' in disc reveals proto-planet

Planets form in the disc of dirt and gas that spins around a new star.
Dr Pinte and his colleagues stumbled upon the new baby planet while trying to understand the disc structure around a young star called "HD163296".
While examining how carbon monoxide gas (CO) was flowing around the star, they noticed a "kink" in its otherwise smooth trajectory.
"We found that the disc deviation corresponded exactly to what a computer simulation of a planet in a disc predicted," Dr Pinte said.
"We're pretty confident that this is the only explanation for what we are seeing in the disc."
Jonti Horner, an astrophysicist at the University of Southern Queensland who was not involved in the study, said the planet was an exciting discovery. He likened it to seeing a human baby kick inside the womb.

New clues and mysteries about planet formation

The baby planet is further from its star than any other planet yet discovered, Dr Pinte said.
"Nobody was expecting to find such a massive planet so far from the star. There's not much material to form a planet out there."
At eight times the distance between Neptune and the Sun, the planet's orbit is not really comparable to anything in our solar system, he added.
"But it can be useful to understand if our solar system is typical, or if it's an exception."
Professor Horner agreed that the novelty of this discovery can shine a new light on our own solar system.
"Results like this reveal that the diversity of planets is far greater than we ever would have imagined," he said.
HD163296 is approximately 4 million years old, 330 light years away from our Sun and already twice its size.
"It's a tantalising clue that massive stars do form massive planets," he said.
"It might be a common theme among exoplanets that more massive stars can have more distant, more massive planets."

Baby planet boom imminent

Astronomers detected the still-forming planet while sifting data from ALMA: a network of 66 interconnected radio dishes built high in the Atacama Desert, where the air is frigid and dry.
It has a crystal-clear view of the heavens and a level of precision that only comes from combining multiple instruments.
"It's only possible to [detect] it with high resolution observations, and with a lot of antennas which have only been available in the last few years," Dr Pinte said.
The data in this study was collected in 2012 and 2015. ALMA is only just reaching its full capabilities at the moment, said Dr Pinte.
"The dataset we used is only average resolution for ALMA, so that means that potentially ALMA will be able to discover many more of these very young planets."
Professor Horner said the study was a lovely example of how modelling and observation can go hand in hand to explain the previously unexplained.
"There's still so much to learn — and that's why results like this are so exciting. They open our eyes to the full variety of what is out there."