The discovery of a new black hole is always an interesting event; this time, researchers from the Instituto de Astrofísica de Canarias (IAC) have managed to get the first spectroscopic data from the binary system in case, and found that it contains a black hole, which is quite rare, at least according to out knowledge of the Universe.
X-ray binaries are formed from a compact object (neutron star, black hole, etc) and a regular star. The more compact object slowly ‘sucks’ material from the other star and adds it to its own, creating a spiral disk around it. However, out of the estimated 5.000 binary systems in our galaxy, no more than 20 contain a black hole.
The system in case, XTE J1859+226, is a ‘transient X-ray binary’.
“Transient X-ray binaries are characterised for spending most of their life in a state of calmness, but occasionally entering eruption stages, during which the rhythm of acretion of matter toward the black hole is triggered,” Jesús Corral Santana explains, an astrophysicist from the IAC, who led the work published in the Monthly Notices of the Royal Astronomical Society (MNRAS).
If the compact object is more than three times heavier than the Sun, then it can only be a black hole, and in this case, the object was 5.4 times heavier than our star.
“With this result we add a new piece to the study of the mass distribution of black holes. The shape of this distribution has very important implications for our knowledge about the death of massive stars, the formation of black holes, and the evolution of X-ray binary systems,” the IAC astrophysicist adds.