New discovery could transform our understanding of stars in the Universe

Researchers, including those from the University of Leed's School of Physics and Astronomy, have discovered new evidence that massive Be stars, which are mainly thought to exist in double stars - could in fact be "triples". This discovery could revolutionise the way astronomers understand some of the biggest and most common stars in the Universe. 

Be stars a subset of B stars, are surrounded by a characteristic disc made of gas, akin to the iconic rings of Saturn. Although these intriguing objects have been known for about 150 years, until now, no one has known how they were formed.

PhD student and corresponding author of the research, Jonathan Dodd, said, "The best point of reference for that is if you've watched Star Wars, there are planets where they have two Suns."

By analysing data gathered by the European Space Agency's Gaia satellite, researchers claim to have found evidence that these stars actually exist in triple systems - with three bodies interacting instead of just two.

"The fact that we do not see them might be because they are now too faint to be detected," said Principal Investigator Prof Rene Oudmaijer.

The researchers then looked for companion stars that are further away in another dataset and found that at these larger separations, the rate of companion stars is very similar between the B and Be stars.  Based on this, the team concluded that in many cases a third star is coming into play, forcing the companion closer to the Be star, close enough that mass can be transferred from one to the other and form the characteristic Be star disc.

According to the researchers, the "vampire" Be star sucks in so much of their mass that they become too small and faint to be detected.

The team also included 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. The team received funding from the Science and Technology Facilities Council (STFC).