In theory they should exist in the universe, but no one had been able to find one. However, now a team of Spanish researchers has located the first binary system formed by a black hole and a ‘spinning top’ star , as has just been published in the scientific journal Nature.
But what exactly is a ‘spinning top’ star? In our galaxy , more than 80 Be stars (known as ‘spinning top’ stars) are known, forming binary systems together with neutron stars . As Jorge Casares, from the Instituto de Astrofísica de Canarias (IAC) and Universidad de La Laguna (ULL) and one of the discoverers explains, “ their particularity is their high centrifugal force, they rotate on themselves at a very high speed , close to their limit. breaking, as if they were cosmic tops ”. This is the case of this star, known as MWC 656, which is located in the constellation Lacerta (the Lizard) at 8,500 light years from Earth and whose surface rotates at more than a million kilometers per hour.
Researchers began studying this star in 2010, when transient gamma-ray emission was detected that appeared to come from it. “No more gamma emission was observed, but we discovered that it was part of a binary system,” explains Marc Ribó, from the Institut de Ciències del Cosmos (ICC) of the University of Barcelona.
By analyzing in detail the spectrum of the emissions, the researchers obtained the data of the star’s companion in this binary system . Its density was extraordinarily high (between 3.8 and 6.9 times the solar mass) which, taking into account that it is not visible, it could only be a black hole, the researchers point out.
Scientists believe that it is not an isolated event in the universe, but that many more binary systems of this type could exist. As Jorge Casares, one of the researchers involved in the study, points out, “ we think that these systems are much more abundant but difficult to detect , since black holes feed on the gas expelled by the star Be ‘silently’, that is to say , without emitting much radiation. We hope to be able to confirm this fact with the detection of other systems in the Milky Way and in nearby galaxies with larger diameter telescopes, such as the Gran Telescopio de Canarias ”.
