Astronomers discover closest black hole to earth
Gemini North telescope on Hawai'i reveals first dormant, stellar-mass black hole in our cosmic backyard
Astronomers using the International Gemini Observatory, operated by NSF's NOIRLab, have discovered the closest-known black hole to Earth. This is the first unambiguous detection of a dormant stellar-mass black hole in the Milky Way. Its close proximity to Earth, a mere 1600 light-years away, offers an intriguing target of study to advance our understanding of the evolution of binary systems.
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 InternationalGemini Observatory, operated by NSF's NOIRLab, have discovered the closest black hole to Earth, which the researchers have dubbed Gaia BH1. This dormant black hole is about 10 times more massive than the Sun and is located about 1600 light-years away in the constellation Ophiuchus, making it three times closer to Earth than the previous record holder, an X-ray binary in the constellation of Monoceros. 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, an astrophysicist at the Center for Astrophysics | Harvard & Smithsonianand the Max Planck Institute for Astronomy, and 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."
https://www.sciencedaily.com/releases/2022/11/221104113504.htm
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