A team of astronomers from the European southern Observatory (ESO) and other institutions have discovered a black hole, located only 1,000 light-years from Earth. Black hole closer to our Solar system than any other found to date, and is part of a triple system, which can be seen with the naked eye. The team found evidence of the presence of an invisible object, tracing two of its companion star using the 2.2-meter telescope MPG/ESO at La Silla Observatory ESO in Chile. They say that this system may be just the tip of the iceberg, as the future may be found many such black holes.

“We were completely surprised when they realized that this is the first star system with black hole, which can be seen with the naked eye,” says Peter Hadrava, honored worker of the Academy of Sciences of the Czech Republic in Prague and co-author of the study. Located in the constellation of the Telescope, the system is so close to us that its star can be seen from the southern hemisphere dark clear night without binoculars or a telescope. “This system contains the nearest to the Earth a black hole that we know of,” the scientist said ESO Thomas Rivinius, who led the study, published today in the “Astronomy & Astrophysics”.

Initially the team observed the system, called HR 6819, in the study of systems with two stars. However, analyzing their observations, they were stunned to find a third, previously unknown body of HR 6819: a black hole. Observations with the FEROS spectrograph on the 2.2-meter telescope MPG/ESO at La Silla showed that one of the two visible stars rotates around an invisible object every 40 days, while the second star is at a large distance from the inner pair.

Dietrich Baade, honorary astronomer at ESO in Garching and co-author of the study, said: “Surveillance is needed to determine the 40 day period was spread over several months. This was only possible thanks to an innovative scheme monitoring service ESO”.

Hidden black hole in HR 6819 – one of the first found black holes of stellar mass that does not interact with the environment and therefore look truly black. But the team can determine its presence and calculate its mass by studying the orbit of stars in the inner pair. “Invisible object whose mass is 4 times greater than the mass of the Sun, can only be a black hole,” says Rivinius based in Chile.

To date, astronomers have discovered only a few dozen black holes in our galaxy, almost all of which strongly interact with the environment and make its presence known by emitting powerful x-ray radiation in this interaction. But scientists estimate that during the existence of the milky Way, many other stars went to black d��ry, after the end of his life. The opening of the quiet, invisible black hole in HR 6819 gives hints about where there might be numerous hidden black holes in the milky Way. “There must be hundreds of millions of black holes, but we only know about very few. Knowing what to look for should help us to look for them better,” says Rivinius. Baade adds that the discovery of a black hole in the ternary system are so close indicates that we see only the “tip of the exciting iceberg”.

Astronomers now believe their findings could shed light on the second system. “We realized that a different system, called LB-1, can also be such a triple, although we need more observations to tell,” says Marianne heida, researcher at ESO and a co-author. “LB-1 is a little farther from the Earth, but still pretty close in astronomical terms, so this means that there are probably a lot more of these systems. Finding and studying them, we can learn much about the formation and evolution of these rare stars that begin their lives with a mass of about 8 solar masses and end up with a supernova explosion which leaves a black hole”.

The discovery of these ternary systems with inner pair and a distant star can also give clues about the violent cosmic mergers that emit gravitational waves, powerful enough to be detected on Earth. Some astronomers believe that the merger can occur in systems with a configuration similar to HR 6819 or LB-1, but where the inner pair consists of two black holes or black holes and neutron stars. Although the objects of HR 6819 and LB-1 have only one black hole and don’t have neutron stars, these systems will help scientists understand how there are stellar collisions in triple systems of stars.

This study was presented in the article "the Triple system of the naked eye with geaccrediteerde black hole in the inner binary system", published today in the journal Astronomy & Astrophysics .