The galaxy is full of HEAVYWEIGHTS
An excess of massive stars could change our view of the Milky Way
A new study of heavyweight stars has shown that our Galaxy has an excess of high-mass stellar objects, forcing researchers to rethink their assumptions about the Milky Way’s composition. It could also affect the number of gravitational waves that astronomers expect to be able to see.
The team behind the study examined the star-forming region 30 Doradus using ESO’s Very Large Telescope. They observed over 1,000 massive stars, 250 of which were found to have masses 15-200 times that of the Sun – many more high-mass stars than had been expected.
The team was aiming to measure the initial mass function (IMF) – a measure of the distribution of masses within a particular stellar population. But in most places in the Galaxy high-mass stars are relatively rare, so measuring their precise number is difficult; stars over 10 solar masses make up just one per cent of the stellar population.
To find enough massive stars to undertake a study, the team looked toward 30 Doradus, a large, local star-forming region. After studying the region, the researchers found that its IMF was much more weighted to the massive end than previously thought. The finding could have implications for our understanding of how the radiation and strong stellar winds produced by these massive stars affect their surroundings – a process known as feedback – and also for how these giants end their lives in supernovae, seeding the Universe with the heavy elements needed to form planets.
“To quantitatively understand all these feedback mechanisms, and the role that massive stars play in the Universe, we need to know how many of these behemoths are born,” says Phillipp Podsiadlowski, from the University of Oxford.
“The finding could change our view of the cosmos, as more large stars mean more supernovae, potentially altering the chemical balance of the Universe,” says the study’s lead author Fabian Schneider also from the University of Oxford.
“Also, the formation rate of black holes might be increased by 180 per cent, directly translating into a corresponding increase of binary black hole mergers that have recently been detected via their gravitational wave signals.” www.eso.org