The discovery of the “triple star” could revolutionize the understanding of stellar evolution

A groundbreaking new discovery by University of Leeds scientists could change the way astronomers understand some of the largest and most common stars in the universe. The paper, titled “Gaia reveals divergence in the binary of B and Be stars on small scales: evidence for mass transfer that causes the Be phenomenon,” was published in the journal. Monthly Notices of the Royal Astronomical Society.

PhD research. student Jonathan Dodd and Professor Rene Odemeyer, from the university’s School of Physics and Astronomy, point to intriguing new evidence that massive Be stars – hitherto thought to be contained in double stars – could in fact be “triples”.

This remarkable discovery could revolutionize our understanding of objects – a subset of B stars – which are an important “test bed” for developing theories about how stars evolve in general.

These Be stars are surrounded by a distinctive disk made of gas, similar to the rings of Saturn in our solar system. Although Be stars have been known for about 150 years, having been first identified by the famous Italian astronomer Angelo Cecchi in 1866, until now no one knew how they formed.

The consensus among astronomers so far is that the disks form due to the rapid rotation of Be stars, and that this could itself be caused by the interaction of stars with another star in a binary system.

Triple systems

“The best reference point for this is if you’ve watched Star Wars, there are planets that have two suns,” said Mr. Dodd, the paper’s author.

But now, by analyzing the data from… European Space Agency’s Gaia satelliteScientists say they have found evidence that these stars actually exist in triple systems, where three objects interact instead of just two.

Mr Dodd added: “We have observed the way stars move across the night sky, over longer periods such as 10 years, and shorter periods of around six months. If a star moves in a straight line, we know there is only one star, but if there More than one, and we’ll see a slight wobble, or at best, a vortex.

“We applied this to the two groups of stars we’re looking at — B stars and Be stars — and what we found, confusingly, is that initially Be stars seem to have a lower companion rate than B stars. This is interesting because we expect them to have a higher rate. ”

However, lead researcher Professor Odemeyer said: “The fact that we don’t see them may be because they are now too faint to be detected.”

Mass transfer

The researchers then looked at a different set of data, looking for distant companion stars, and found that at these larger separation distances, the rate of companion stars is very similar between B and Be stars.

From this, they were able to deduce that in many cases a third star comes along, forcing the companion closer to the Be star, close enough that mass can be transferred from one star to another and form the characteristic Be star disk. This could also explain why we don’t see these companions anymore; It became too small and faint to be detected after Be’s “vampire” star absorbed much of its mass.

This discovery could have huge implications for other areas of astronomy, including our understanding of black holes, neutron stars, and sources of gravitational waves.

Professor Odemeijer said: “There is a revolution happening in physics at the moment around gravitational waves. We have only been observing these gravitational waves for a few years, and they have been found to be caused by merging black holes.

“We know that these mysterious objects – black holes and neutron stars – exist, but we don’t know much about the stars they will become. Our findings provide a clue to understanding the sources of these gravitational waves.”

He added: “Over the past decade or so, astronomers have found that binaries are a very important element in stellar evolution. We are now moving more towards the idea that they are more complex than that, and that triple stars need to be considered.”

“In fact, threes have become the new twos,” Odemeijer said.