2023-11-21 11:33:23
An artist’s impression composed of a star with a disk around it (a “vampire” Be star; foreground) and its companion star that has had its outer parts stripped (background). – ESO/L. CALÇADA
MADRID, 21 Nov. (EUROPA PRESS) –
Astronomers have gathered intriguing new evidence that massive Be stars – until now thought to exist mainly in double stars – they may actually be ‘triples’.
The remarkable discovery could revolutionize our understanding of these objects (a subset of B stars) that are considered an important “testbed” for developing theories about how stars evolve more generally.
These Be stars are surrounded by a characteristic disk made of gas, similar to the rings of Saturn in our own solar system. And although the stars Be They have known each other for about 150 years (they were first identified by the renowned Italian astronomer Angelo Secchi in 1866), Until now no one has known how they were formed.
Until now, the consensus among astronomers has been that the disks are formed by the rapid rotation of Be stars, and that this in turn may be caused by the interaction of the stars with another star in a binary system.
Jonathan Dodd, a Physics and Astronomy student at the University of Leeds and corresponding author of the research, said: “The best reference point for this is that if you’ve seen Star Wars, there are planets that have two suns.”
But now, by analyzing data from ESA’s Gaia satellite, scientists say they have found evidence that these stars actually exist in triple systems, with three interacting bodies instead of just two. The findings Monthly Notices of the Royal Astronomical Society.
“We look at the way stars move across the night sky, for longer periods, like 10 years, and shorter periods, about six months. If a star moves in a straight line, we know there is only one star. star, but If there is more than one, we will see a slight wobble or, at best, a spiral.
“We applied this to the two groups of stars we’re looking at, the B stars and the Be stars, and what we found, confusingly, is that at first it appears that the Be stars have a lower rate of companions than the B stars. “This is interesting because we would expect them to have a higher rate.”
However, lead researcher Professor Rene Oudmaijer said: “The fact that we don’t see them could be because they are now too faint to be detected.”
The researchers then looked at a different set of data, looking for companion stars that were farther apart, and found that at these larger separations, 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 into play, forcing the companion to approach the star Be, close enough so that mass can be transferred from one to the other and form the characteristic disk. of the star Be. This could also explain why we no longer see these companions; have become too small and faint to be detected after the “vampire” star Be has absorbed much of its mass.
The discovery could have enormous impacts on other areas of astronomy, including our understanding of black holes, neutron stars and the sources of gravitational waves.
Professor Oudmaijer said: “There is currently a revolution going on in physics around gravitational waves. We have only been observing these gravitational waves for a few years. and it has been discovered that they are due to the merger of black holes.
“We know that these enigmatic objects (black holes and neutron stars) exist, but we don’t know much about the stars that would become them. Our findings provide a clue to understanding these sources of gravitational waves.”
He added: “Over the last decade, astronomers have discovered that binarity is an incredibly important element in stellar evolution. Now we are moving more towards the idea of that it is even more complex than that and that triple stars need to be considered.
“In fact,” said Oudmaijer, “triples have become the new binaries.”
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