Many more massive stars than expected
An enormous star-forming region in the Large Magellanic Cloud, a satellite galaxy of the Milky Way, contains far more massive stars than previously thought possible. This is the result of research performed by an international team of astronomers, among whom Alex de Koter and Selma de Mink of the Anton Pannekoek Institute of the University of Amsterdam. The astronomers publish their results in Science magazine.
Record amount of stars
The research presents very detailed measurements of nearly three hundred massive stars in the famous star-forming region 30 Doradus, also known as the Tarantula Nebula. The region is situated in the Large Magellanic Cloud a satellite galaxy of the Milky Way, 180.000 light years away from us. In the past millions of years, a ‘baby boom of stars’ took place in the nebula. This makes it especially suited to learn about the origin of the universe.
Alex de Koter: ‘We worked on this study, measuring a record amount of stars of 15 solar masses and more, for eight years. What’s unique is that we determined the mass of each star individually. Other researchers often look at the combined light of all the heavy stars to estimate their mass distribution, which is an indirect and therefore less reliable method.’
Thirty percent more
The astronomers conclude that the nebula contains thirty percent more massive stars than predicted by the widely used law of Salpeter (1955). Though massive stars only exist for a short while, a few tens of millions of years at most, they form neutron stars or black holes at the end of their lives after a spectacular supernova explosion, thereby exerting great influence on their wide surroundings.
Selma de Mink: ‘This study changes how we see the final stages of heavy stars. If you extend these results, there may be 70 percent more supernovae and even 180 percent more black holes.’
In the future, the researchers would like to verify that their results also hold up in other star forming regions. Also they would like to determine how their findings affect theories on the formation of structure in the universe and the expected amount of phenomena of which we can measure gravitational waves.
An excess of massive stars in the local 30 Doradus starburst. Door: F.R.N. Schneider, H. Sana, C.J. Evans, J.M. Bestenlehner, N. Castro, L. Fossati, G. Gräfener, N. Langer, O.H. Ramírez-Agudelo, C. Sabín-Sanjulían, S. Simón-Díaz, F. Tramper, P.A. Crowther, A. de Koter, S.E. de Mink, P.L. Dufton, M. Garcia, M. Gieles, V. Hénault-Brunet, A. Herrero, R G. Izzard, V. Kalari, D.J. Lennon, J. Maíz Apellániz, N. Markova, F. Najarro, Ph. Podsiadlowski, J. Puls, W.D. Taylor, J.Th. van Loon J.S. Vink, C. Norman. In: Science, 5 januari 2018. Link to publication