An international team of astronomers, in which Spanish researchers have also participated, has discovered a surprising abundance of massive stars in a neighboring galaxy, specifically in the 30 Doradus region of the great Magellanic Cloud galaxy.
The finding has important consequences for our understanding of how stars transformed the pristine universe we live in today. “ We were surprised when we realized that 30 Doradus has formed many more massive stars than expected, ” says Fabian Schneider, from the Department of Physics at the University of Oxford (UK) and leader of the study published in the journal Science.
Thanks to the Very Large Telescope (VLT) of the European Southern Observatory (ESO) and within the VLT-FLAMES Tarantula Survey , astronomers observed almost 1,000 massive stars in 30 Doradus, a gigantic stellar nursery also known as the Tarantula Nebula. The team used detailed analyzes of about 250 stars with masses between 15 and 200 times the mass of our Sun to determine the distribution of massive stars born in 30 Doradus.
Massive stars are particularly important to astronomers because of the enormous influence they have on their environment: they can explode into spectacular supernovae at the end of their lives, forming some of the most exotic objects in the universe: neutron stars and black holes.
Aside from being surprised by the large number of massive stars discovered, scientists are also stunned by their density (up to 200 solar masses). Above all, considering that the existence of stars of up to 200 solar masses was highly controversial. This study shows that a maximum star birth mass of 200-300 solar masses is likely.
Stars get rarer – or exotic – the more massive they are. Until now, we believed that most of the stellar mass was found in low-mass stars and that less than 1% of all stars were born with masses that exceed ten times that of the Sun. It is clear that we lacked information.
The largest local star-forming region
30 Doradus is home to some of the most massive stars ever discovered . By studying this region, the researchers determined the masses of massive stars with unique observational, theoretical, and statistical tools. This large sample allowed scientists to show that massive stars are much more abundant than previously thought.
“In fact, our results suggest that most of the stellar mass is no longer at low levels,” explains Chris Evans of the Center for Astronomy Technology at the UK Council for Science and Technology Facilities and a co-author of the study.
“Our results have far-reaching consequences for understanding our cosmos: there may be 70% more supernovae, a tripling of chemical yields, and four times the ionizing radiation of massive stellar populations. In addition, the rate of hole formation Black holes could increase by 180%, which translates directly into an increase in binary black hole mergers that have recently been detected through their gravitational wave signals, “concludes Schneider.
Referencia: F.R.N. Schneider el al., “An excess of massive stars in the local 30 Doradus starburst,” Science (2018). science.sciencemag.org/cgi/doi … 1126/science.aan0106
Image credit: NASA
