Astronomers Discover Earth’s Nearest Known Black Hole

Astronomers have just announced the discovery of Earth’s nearest known black hole, and it’s visible with the naked eye. The black hole—located in the HR 6819 star system—has two companion stars, which means despite its invisibility, it can be tracked. Although this newly discovered black hole is still 1,000 light-years away, so there is no need to panic!

Science News picked up the discovery, which was outlined in a recent paper published in the journal, Astronomy & Astrophysics. The team of authors behind the paper, including Petr Hadrava at the Academy of Sciences of the Czech Republic in Prague, European Southern Observatory scientist Thomas Rivinius, et al. did not expect to find this relatively nearby blackhole. In fact, the team’s original aim was to study HR 6819 as a part of a research project on binary star systems.

“We were totally surprised when we realised that this is the first stellar system with a black hole that can be seen with the unaided eye,” Hadrava said in an ESO press release. The blackhole in HR 6819—which itself is located the Telescopium constellation—is only one of very few that do not interact violently with nearby matter, and therefore appears to be “truly black.”

The unnamed black hole is four times the mass of the Sun, and forms a “massive hierarchical triple system” with its two companion stars. The dynamic that has developed between the black hole and its companion star duo is visualized in the video up top. Note that the inner greenish-blue line indicates the movement of the system’s inner star, and the red line indicates the movement of the black hole; beyond those two, entering in toward the end of the video, is the system’s second star.

The authors of the paper note that there is a discrepancy between the number of black holes that are hypothesized to exist, and the number that have been observed. They also think that many other black holes like this one may be discovered in other, similar star systems.

“There must be hundreds of millions of black holes out there, but we know about only very few,” Rivinius says in the ESO press release. Baade added that discovering a black hole in a triple system so close by likely means we are seeing “the tip of an exciting iceberg.”

What do you think about our newly discovered black hole neighbor? Is this going to be the closest black hole to Earth we’ll ever find, or do you think there are ones lurking much closer? Let us know your thoughts in the comments!

Feature image: ESO/L. Calçada

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