Turbulent Relationship among Massive Stars

The most massive stars in the universe have paths that are not as calm as previously thought; they come very close to neighboring stars and suck material from their companions much like a vampire does or they melt together to become even more massive. These are the most recent findings of an international team of researchers involving the University of Bonn. The results have now been published in the renowned scientific journal “Science“.

An international team of researchers from the USA and Europe including from the University of Bonn under the direction of Dr. Hugues Sana (University of Amsterdam) has discovered that the most massive stars in the universe don’t spend their lives in space as singles as was previously thought. More than two-thirds orbit a partner star. “The orbit paths of the stars are very close together so that the region around these stars is turbulent and by far not as calm as previously thought,” says Professor Norbert Langer from the University of Bonn. What happens is that one star can suck the material out of its companion like a vampire or both stars can melt to become an even larger massive star. This is revealed in a current study on the lives of massive stars, a study which Dr. Norbert Langer, Prof. Dr. Robert Izzard and Fabian Schneider worked on together with three other scientists from the Argelander Institute for Astronomy at the University of Bonn.

Abbildung: ESO/L. Calçada/S.E. de Mink

Ten years of observations using one of the world’s largest telescopes

Astronomers evaluated more than ten years’ worth of observations using one of the world’s largest telescopes, the Very Large Telescope (VLT) in Chile’s Atacama Desert. “The spectacular new research findings could only have been gathered based on one of the most extensive observation campaigns in this area,” says Professor Robert Izzard. A total of 71 massive stars in six young galactic star clusters were observed for years. Through close-knit monitoring, researchers were able to determine the paths of over three-quarters of the double stars discovered which led to unique precision. “The current study reveals that the fast majority of all massive stars spend their lives with a partner,” states Fabian Schneider, the third scientist based in Bonn. Over time, roughly one-third of the star systems melts with their companion, while the other two-thirds transfer material to its partner.

Massive stars, also called spectral class O stars because of their characteristics are the brightest and the most short-lived stars in the universe. In the beginning they are more than 15 times as massive as our Sun. The end of their life is marked by spectacular supernova explosions or gamma ray bursts. They account for a large part of all the heavy elements in the universe. “The new insight into the lives of massive stars has a direct impact on the understanding of the final stages most massive stars experience,” says Professor Langer. The gigantic explosions at the end of a star’s life can be observed from almost all corners of the universe. This underscores the importance of the new findings which have now been published.

Science news reference: 

Binary Interaction Dominates the Evolution of Massive Stars. H. Sana, S. E. de Mink, A. de Koter, N. Langer,   C. J. Evans, M. Gieles, E. Gosset, R. G. Izzard, J.-B. Le Bouquin, and F. R. N. Schneider. Science 27 July 2012: 444-446. DOI:10.1126/science.1223344


Science news source: 

University of Bonn