Astronomers have witnessed the birth of a pair of planets 400 light years away.
The discovery was made after researchers mapped gases in three dark rings surrounding a young, known as HD 163296
They mark spaces where planets are thought to have formed from dust and gas around the star.
The finding may help scientists to better understand how planets form in distant solar systems.
Pictured here is a telescopic image of the star HD 163296 and its protoplanetary disk as seen in dust. The team claim that planets are responsible for clearing the outermost rings of any trace of dust. But is the innermost ring that they were most interested in
The target star for the astronomers’ study is known as HD 163296.
It is nearly 400 light years away and is best observed from the Southern hemisphere.
While the two outer rings have evidence of planets forming, the innermost ring remains a mystery
It has far more carbon monoxide than the outer two, leading the team to believe no planets exist within the ring.
‘The inner gap is mysterious,’ Dr Isella, lead researcher and assistant professor at Rice University, said.
‘Whatever is creating the structure is removing the dust but there’s still a lot of gas.’
Astronomers have spotted gases in three dark rings around a distant star for the first time. The rings mark spaces where planets are thought to have formed from dust and gas around the star. Pictured here is an artist’s impression of the protoplanetary disk surrounding the young star HD 163296
The team claim that planets – probably gas giants with masses comparable to Saturn – are responsible for clearing the outermost rings of any trace of dust.
‘Of the material that formed this disk, about one per cent is dust particles and 99 per cent is gas,’ Dr Isella said.
‘So if you only see the dust, you cannot tell if a ring was formed by a planet or another phenomenon.
‘In order to distinguish and really tell if there are planets or not, you need to see what the gas is doing, and in this study, for the first time, we can see both the dust and the gas.’
HOW DO PLANETS FORM?
According to our current understanding, a star and its planets form out of a collapsing cloud of dust and gas within a larger cloud called a nebula.
As gravity pulls material in the collapsing cloud closer together, the center of the cloud gets more and more compressed and, in turn, gets hotter. This dense, hot core becomes the kernel of a new star.
Meanwhile, inherent motions within the collapsing cloud cause it to churn.
As the cloud gets exceedingly compressed, much of the cloud begins rotating in the same direction.
The rotating cloud eventually flattens into a disk that gets thinner as it spins, kind of like a spinning clump of dough flattening into the shape of a pizza.
These ‘circumstellar’ or ‘protoplanetary’ disks, as astronomers call them, are the birthplaces of planets.
The first exoplanet – planets that lie outside of our solar system – was discovered only 20 years ago, but thousands of planets are now in the database.
In this time, scientists have drastically improved their ability to analyse them for their potential to host alien life.
One aim of the Atacama Large Millimeter Array (ALMA) in Chile, the world’s largest radio telescope used in research, is to study protoplanetary systems dotted with exoplanets.
Their mechanics will help scientists understand how the planets like Earth formed.
And part of their research involves investigating the strange rings found around stars like HD 163296.
With the new observations, it has been revealed that these rings are formed as new exoplanets are born around the star, hoovering up dust and gas around the star for resources.
The researchers’ results lay the foundation for new observations of the strange rings.
The team will spend over 50 hours studying other stars and exoplanets to decipher just how new planets form.
Dr Isella said the researchers will also return to HD 163296 to learn what other elements make up the disk and rings.
‘Now the question is whether all the protoplanetary disks are like this,’ says Dr Isella.
‘Do they all have this structure?
‘There is the concern that this object is a freak,’ Isella said.
The scientists were particularly interested in HD 163296 because of its unusual properties.
Its outer rings are 100 and 160 astronomical units from the star, with each unit equivalent to the distance from the center of the sun to Earth.
Rings with distances of 100 and 160 astronomical units are much further from the star than previously thought possible for planet formation.
The star is too far from Earth for direct observation of the planets that may have formed around it.
Yet evidence from the new study shows that planets are indeed likely to be there.
The planets clear dust and gas from the outer rings as they form.
But the formation of new planets may not be the only trigger for the star’s strange rings.
The researchers suspect a ‘dead zone’ around HD 163296 may also be responsible for the rings.
This dead zone allows gas and dust to condense into a Saturn-like ring at the edge of the dark zone rather than a planet.
The ring may also appear at the carbon monoxide ‘frost line’ where the gas becomes cold enough to condense.
The work appears this week in Physical Review Letters