Exoplanet found around giant binary stars baffles scientists

Giant exoplanet binary stars

So far, scientists have discovered hundreds of exoplanets, however, it seemed that none of them could exist around stars with masses more than three times the mass of the Sun. In fact, this appeared to be impossible both theoretically and in practice. But that may not be the case, the Very Large Telescope of the European Southern Observatory may have just found a new planet, which has perplexed cosmogonists.

Indeed, scientists have just uncovered a planet in the star system b Centauri that defies this commonly held belief.

Researchers now believe that either b Centauri b should not exist at all, or that they know much less about how planets develop than they did previously believe. In any event, the finding of a massive planet in the massive star system b Centauri offers a no less massive conundrum than the discovery of the planet itself.

Never before have astronomers been able to locate an exoplanet in a star system that is both hot and huge. The discovery was published in the journal “Nature” by a team headed by Markus Janson of Stockholm University.

Because of its name, the system b Centauri is often confused with others. It is neither our neighboring star system Alpha Centauri, which contains the brightest star in the constellation of Centaur, nor Beta Centauri, which contains two white-blue supergiants in a double system.

The star system b Centauri is a binary star system located at a distance of around 325 light-years from Earth. It can only be spotted in the southern sky since it is located at the border of the centaur constellation, which is visible from Earth. b Centauri A, a B-class star, has a temperature more than three times that of our Sun, making it one of the most massive stars in the universe. The binary star system b Centauri has between six and ten solar masses in total.

In the picture below, you can see the newly discovered exoplanet b Centauri b. The first b refers to the star designation, whilst the second refers to the planet itself. The picture was taken by the SPHERE instrument on the Very Large Telescope (VLT) of the European Southern Observatory (ESO), which Markus Janson’s team used to confirm their findings. Later, the researchers were able to discover the planet in archival data that had been stored for 20 years.

b centauri b
The exoplanet b Centauri b, which was recently discovered and directly seen, is shown by an arrow on this diagram. The binary star system b Centauri is seen as a huge, brilliant object in the top left corner of the image. The circles that appear in the surroundings are caused by optical artifacts.

The exoplanet itself, like its huge parent stars, is an extreme exemplar of its kind: it has ten times the mass of Jupiter and is orbiting its double star at a distance 100 times greater than Jupiter’s distance from the Sun. As a result, scientists believe that it is unlikely to have been generated in a previously recognized manner.

Alternative scenarios, on the other hand, fail to explain the planet because the binary stars shine too intensely and too brightly for planets to form in their proximity and eventually migrate farther away from them, as seen in Figure 1. Other mechanisms, it seems, were in operation.

According to Janson’s study group, it is possible that b Centauri b originated in another star system and was caught by b Centauri.

“Trying to figure out how this may have happened would be an interesting undertaking. At the time, the situation is still a puzzle,” Janson concluded.