A revolutionary new discovery by scientists at the University of Leeds could transform the way astronomers understand some of the largest and most common stars in the universe. The paper, “Gaia reveals small-scale binary differences between B and Be stars: evidence for mass transfer driving the Be phenomenon,” was published in the journal Monthly Notices of the Royal Astronomical Society.

Candidate research. Student Jonathan Dodd and Professor René Oudmaier from the university’s School of Physics and Astronomy point to intriguing new evidence that massive Be stars, until now thought to exist as binary stars, may actually be “triplets”.

This remarkable discovery could revolutionize our understanding of objects (a subset of B stars) that are considered an important “testing ground” for developing theories about how stars evolve more generally.

These Be stars are surrounded by a characteristic disk of gas similar to the rings of Saturn in our solar system. Although Be stars have been known for nearly 150 years (they were first detected by the famous Italian astronomer Angelo Secchi in 1866), no one knew how they were formed until now. Astronomers still agree that the disks are formed by the rapid rotation of Be stars, which may result from the star’s interaction with another star in the binary system.

Ternary systems

Mr Dodd, the study’s lead author, said: “The best reference for this is if you’ve watched Star Wars there are planets with two suns.”

But now, after analyzing data from the European Space Agency’s Gaia satellite, scientists say they have found evidence that these stars actually exist in triple systems of three interacting objects rather than two.

Mr Dodd added: ‘We watched stars move across the night sky over longer periods of about 10 years and shorter periods of about six months. If the star is moving in a straight line we know there is only one star, but if there is more than one star we will see a slight wobble or at best a spiral.

“We applied this to the two groups of stars we looked at (B stars and Be stars) and found that what was surprisingly misleading was that Be stars initially appeared to have fewer moons than B. This is interesting because we expect them to have a higher ratio.”

But lead researcher Professor Oudmaier said: “The reason we can’t see them may be because they are too weak to be detected at the moment.”

mass change

The researchers then looked for more distant companion stars by looking at another data set and found that the number of companion stars between B and Be stars was very similar at these greater distances.

From this they were able to conclude that in many cases a third star comes into play and pulls the companion Be star closer, close enough for mass to pass from one to the other and form the characteristic disk of the Be star. This may also explain why we can no longer see these moons; After the “vampire” star absorbed most of their mass, they became too small and faint to be detected.

The discovery could have major implications for other areas of astronomy, including our understanding of black holes, neutron stars, and the sources of gravitational waves. Professor Oudmaier said: “There is currently a revolution in physics around gravitational waves. We have only been observing these gravitational waves for a few years, and they have been determined to be caused by the merger of black holes.

“We know that these mysterious objects—black holes and neutron stars—exist, but we know little about the stars that could become them. Our discoveries provide the key to understanding these sources of gravitational waves.”

He added: “Over the past decade astronomers have discovered that duality is an incredibly important element in the evolution of stars. We are now moving towards the idea that it is even more complex than that and triple stars should be considered.” “In fact,” Oudmeier said, “the triplets have become the new binaries.” Source