Astronomers from the European Southern Observatory have discovered another black hole, the closest one to Earth known to date. What's even interesting, is that they say it can be seen from Earth without needing binoculars.

Located in the constellation of Telescopium, just 1000 light-years from the Earth, the black hole is said to be part of a triple system so close to us that its stars can be viewed from the southern hemisphere on a dark, clear night with just the naked eye.

The team discovered evidence for the initially unseen object by tracking its two companion stars using the MPG/ESO 2.2-meter telescope at ESO's La Silla Observatory in Chile. Many astronomers believe that this discovery could just be the tip of the iceberg, as many more similar black holes could be uncovered in the future.

According to Petr Hadrava, Emeritus Scientist at the Academy of Sciences of the Czech Republic in Prague and co-author of the research, the team was surprised when they came to know that it was the first stellar system with a black hole that could be seen without the use of special devices.

ESO scientist and study leader, Thomas Rivinius, says that the system holds the nearest known black hole to Earth. The study was published today in Astronomy & Astrophysics.

An Unexpected Discovery

At the outset, the team observed the system, called HR 6819, as part of a study of double-star systems. However, as they evaluated their observations, they were astonished when they revealed a third, previously unknown body in HR 6819, which was a black hole.

The investigations with the FEROS spectrograph on the MPG/ESO 2.2-metre telescope at La Silla displayed that one of the two visible stars orbits a hidden object every 40 days, while the second star is at a considerable distance from this inner pair.

The hidden black hole in HR 6819 is one of the very first stellar-mass black holes found that do not relate destructively with their environment. Because of its harmonious state, it appears to be truly black.

The team was able to spot its existence and calculate its mass by studying the orbit of the star in the inner pair. According to Rivinius, who is based in Chile, an invisible object with a mass at least four times that of the Sun can only be a black hole.

As of the moment, astronomers have only located a couple of dozen black holes in our galaxy. Nearly all of these black holes actively interact with their environment and release powerful X-rays in this synergy.

Exciting New Discoveries to Come

Rivinius believes that there must be a cornucopia of black holes waiting to be discovered. He says that knowing what to look for should put astronomers in a better position of finding them.

Dietrich Baade, Emeritus Astronomer at ESO in Garching and co-author of the study, adds that finding a black hole in a triple system nearby could also mean that we are seeing just "the tip of the iceberg."