Huge stars are forming in completely unexpected ways in our own galaxy and beyond, new research suggests.
Scientists had long expected that larger stars form in much the same way as smaller ones. But a new study suggests that something unexplained is happening to those high-mass stars, and they are forming in a way vastly different to how we expected.
In lower-mass stars – which make up most of those we can see in detail – there seems to be a simple relationship between the mass of the star-forming clouds of dust and gas, and the mass of the star itself once it is born.
But the new study suggests that high-mass stars do not behave in that way. The finding adds extra mystery to the already unknown relationship of what decides how stars eventually grow to a certain mass.
The new findings will force researchers to rethink their understanding of how high-mass stars are formed in the universe.
All across the known universe, huge molecular clouds made of dust and gas collapse and then stick together in dense blobs. Those cores then collapse and heat up so hot that they form into stars.
In our own galaxy, the mass of those cores seems to decide the mass of the stars that come out of them. There seems to be a common pattern that can be seen in all such regions.
But scientists have now looked into a different region of clusters elsewhere in the universe, in an attempt to find whether that relationship works in other places too.
They found that the simple relationship we had presumed would hold throughout the universe appears to be wrong, and that the cores are behaving differently elsewhere.
Scientists used the Atacama Large Millimetre/Submillimetre Array (Alma) in Chile to gain an unprecedented insight into a distant star-forming region, named W43-MM1, that lies 18,000 light years away.
By using this extremely sensitive array of telescopes, the team were able to observe star-forming cores with an extraordinary range, from those similar to the mass of our Sun to ones that were 100 times more massive.
To their surprise, the distribution of star-forming cores was completely different to what had previously been observed in nearby regions of the Milky Way.
In particular, they observed an abundance of extremely big stars with huge masses, but fewer smaller stars that are more common within our galaxy.
Co-author of the study Dr Kenneth Marsh, from Cardiff University, said: "These findings were a complete surprise and call into question the intricate relationship between the masses of star-forming cores and the masses of the stars themselves, which has long been assumed.
"As a consequence, the community may need to revisit its calculations regarding the complex processes that dictate how stars are born.
"The evolution of a core into a star involves many different physical interactions, and the results of studies such as this should help us better understand how it all happens."
The study, The unexpectedly large proportion of high-mass star-forming cores in a Galactic mini-starburst, is published in the journal Nature Astronomy.
Additional reporting by agencies
