Astronomers may have caught a relatively nearby star munching on a planet or mini-planets.
A NASA space telescope noticed that the star suddenly started looking a bit strange last year.
The Chandra X-Ray Observatory spotted a 30-fold increase in iron on the edge of the star, which is only 10 million years old, along with pronounced dimming.
Astronomers may have caught a relatively nearby star munching on a planet or mini-planets. This illustration provided by NASA depicts debris surrounding the star RW Aur A, about 450 light-years away from the Earth
‘Computer simulations have long predicted that planets can fall into a young star, but we have never before observed that,’ said lead researcher Hans Moritz Guenther, a research scientist in MIT’s Kavli Institute for Astrophysics and Space Research.
‘If our interpretation of the data is correct, this would be the first time that we directly observe a young star devouring a planet or planets.’
Astronomers have been watching the baby star – in the constellation Taurus – for decades and iron levels weren’t high in 2015 the last time the Chandra telescope looked at it.
The star, called RW Aur A, is 450 light-years away. A light-year is 5.9 trillion miles.
Guenther, a scientist at the Massachusetts Institute of Technology, said he’s never seen anything quite like this before, calling it ‘a lot stranger than we thought we’d be seeing.’
‘We’ve never seen any star that’s changed its iron abundance like that,’ he said.
Guenther said one potential simple explanation is that the star is eating a planet or mini-planets.
He looked at other possible explanations, and of the two that make sense, he prefers the planet-munching one.
Computer simulations show it can happen, but it has never been seen before, he said.
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 centre 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.
‘Much effort currently goes into learning about exoplanets and how they form,’ Guenther says, so it is obviously very important to see how young planets could be destroyed in interactions with their host stars and other young planets, and what factors determine if they survive.’
Outside experts, however, are so far wary.
‘This could be an exciting discovery, but the evidence is circumstantial and not definitive,’ said Harvard’s Avi Loeb.
Guenther’s preferred explanation is speculative, said Alan Boss of the Carnegie Institution of Science, an expert on planets outside our solar system.