There may be more big stars out there than we thought. A study of part of the Large Magellanic Cloud found significantly more huge stars than we would expect to see, which could mean that there are more supernovae and black holes too.
In our galactic neighbourhood, all newborn stars seem to follow the same distribution of masses. There are lots of stars about 15 times the mass of the sun, and exponentially fewer stars with higher masses.
“Stars are formed in a variety of masses, and that distribution follows a well-known relation that’s observed everywhere we look, which is kind of odd and we’re not exactly sure why stars follow that relation,” says at the Rochester Institute of Technology in New York.
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But when at Oxford University and his colleagues measured the masses of 247 large stars in the star-forming region 30 Doradus, the mass distribution did not fit the usual pattern. It had 32 per cent more big stars than predicted – ones with masses more than 30 times that of the sun.
Finding regions like 30 Doradus that deviate from the usual distribution could help us figure out what causes that nearly-universal pattern in the first place.
Big star boom
Right now we only know of one other unusual area like this, Figer says – the Arches cluster, in our own galaxy. Since the mass distribution of a collection of stars depends on how they were formed, “that tells me that maybe there are places where star formation happens in a slightly different way than anywhere else we looked,” he says. How 30 Doradus and Arches are similar and different could help us figure out what causes this big star boom.
The Arches cluster and 30 Doradus are both dense clusters of stars with conditions similar to those in the early universe, so this could also help us learn how some of the very first stars formed.
“If there were more areas like 30 Doradus in the early universe, then the early universe could have contained many more big stars like this than our canonical model says,” says at Australian National University in Canberra.
Big stars have big byproducts, such as supernovae, black holes and high-energy radiation. So, Schneider and his colleagues predict that there might be as many as 70 per cent more supernovae and 2.8 times more black holes than we thought, and 3.7 times as much ionising radiation. More big stars could mean the universe – both in its youth and now – looks different than we expected.
Read more: Milky Way’s baby brother caught copying its star shredding habit
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