Groundbreaking Discovery: Be Stars Likely Part of Triple Star Systems Rather Than Binary
University of Leeds researchers have made a groundbreaking discovery that challenges existing theories on star formation and has significant implications for broader astronomical phenomena such as black holes, neutron stars, and gravitational waves.
Based on data from the Gaia satellite, a new study suggests that massive Be stars, known for their characteristic gas discs, are likely part of triple star systems rather than binary systems as previously thought. This revelation could transform the way astronomers understand some of the biggest and most common stars in the Universe.
The research, led by PhD student Jonathan Dodd and Professor René Oudmaijer from the University’s School of Physics and Astronomy, found intriguing new evidence that massive Be stars, until now mainly thought to exist in double stars, could in fact be “triples.”
Be stars are surrounded by a characteristic disc made of gas – similar to the rings of Saturn in our own Solar System. The origin of these discs has been a mystery for about 150 years, and until now, no one has known how they were formed. The consensus among astronomers so far has been that the discs are formed by the rapid rotation of the Be stars, possibly due to the stars interacting with another star in a binary system.
However, analysis of data from the European Space Agency’s Gaia satellite has revealed evidence that these stars actually exist in triple systems— with three bodies interacting instead of just two. By observing how the stars move across the night sky over long and short periods, the researchers deciphered that in many cases, a third star is coming into play, forcing the companion closer to the Be star. The mass transfer from one star to the other forms the characteristic Be star disc.
The team’s findings could have huge impacts on other areas of astronomy, including our understanding of black holes, neutron stars, and gravitational wave sources. According to Prof Oudmaijer, the discovery provides a clue to understanding gravitational wave sources, which have only been observed for a few years now and have been found to be due to merging black holes.
The groundbreaking research, titled “Gaia uncovers difference in B and Be star binarity at small scales: evidence for mass transfer causing the Be phenomenon,” is published in the Monthly Notices of the Royal Astronomical Society and has been carried out with funding from the Science and Technology Facilities Council.
The team behind the discovery includes PhD student Jonathan Dodd and Prof René Oudmaijer from Leeds, along with University of Leeds PhD student Isaac Radley and two former Leeds academics Dr. Miguel Vioque of the ALMA Observatory in Chile and Dr. Abigail Frost at the European Southern Observatory in Chile.