Astronomers have discovered the closest known black hole to Earth, just 1,600 light-years away. Scientists reported Friday that this black hole is 10 times more massive than our sun. And it’s three times closer than the previous record-holder.
It was identified by observing the motion of its companion star, which orbits the black hole at about the same distance as Earth orbits the sun. The black hole was initially identified using the European Space Agency’s Gaia spacecraft, said Kareem El-Badry of the Harvard-Smithsonian Center for Astrophysics.
El-Badry and his team followed up with the International Gemini Observatory in Hawaii to confirm their findings, which were published in Monthly Notices of the Royal Astronomical Society. The researchers are uncertain how the system formed in the Milky Way. Named Gaia BH1, it’s located in the constellation Ophiuchus, the serpent-bearer.
Black holes are the most extreme objects in the Universe. Supermassive versions of these unimaginably dense objects likely reside at the centers of all large galaxies. Stellar-mass black holes — which weigh approximately five to 100 times the mass of the Sun — are much more common, with an estimated 100 million in the Milky Way alone. Only a handful have been confirmed to date, however, and nearly all of these are ‘active’ – meaning they shine brightly in X-rays as they consume material from a nearby stellar companion, unlike dormant black holes which do not.
Astronomers using the Gemini North telescope on Hawai‘i, one of the twin telescopes of the International Gemini Observatory, operated by NSF’s NOIRLab, have discovered this closest black hole to Earth. The new discovery was made possible by making exquisite observations of the motion of the black hole’s companion, a Sun-like star that orbits the black hole at about the same distance as the Earth orbits the Sun.
“Take the Solar System, put a black hole where the Sun is, and the Sun where the Earth is, and you get this system,” explained Kareem El-Badry, the lead author of the paper describing this discovery. “While there have been many claimed detections of systems like this, almost all these discoveries have subsequently been refuted. This is the first unambiguous detection of a Sun-like star in a wide orbit around a stellar-mass black hole in our Galaxy.”
Though there are likely millions of stellar-mass black holes roaming the Milky Way Galaxy, those few that have been detected were uncovered by their energetic interactions with a companion star. As material from a nearby star spirals in toward the black hole, it becomes superheated and generates powerful X-rays and jets of material. If a black hole is not actively feeding (i.e., it is dormant) it simply blends in with its surroundings.
“I’ve been searching for dormant black holes for the last four years using a wide range of datasets and methods,” said El-Badry. “My previous attempts — as well as those of others — turned up a menagerie of binary systems that masquerade as black holes, but this is the first time the search has borne fruit.” (Newswise/AP)
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