![]() ![]() If we'd missed that narrow window, we would have had to wait another year."Īstronomers' current models of the evolution of binary systems are hard-pressed to explain how the peculiar configuration of Gaia BH1 system could have arisen. "Gemini's ability to provide fast-turnaround observations was critical to the project's success. Measurements at this point are essential to make accurate mass estimates in a binary system," said El-Badry. "When we had the first indications that the system contained a black hole, we only had one week before the two objects were at the closest separation in their orbits. The team relied not only on Gemini North's superb observational capabilities but also on Gemini's ability to provide data on a tight deadline, as the team had only a short window in which to perform their follow-up observations. "We could find no plausible astrophysical scenario that can explain the observed orbit of the system that doesn't involve at least one black hole." "Our Gemini follow-up observations confirmed beyond reasonable doubt that the binary contains a normal star and at least one dormant black hole," elaborated El-Badry. The Gemini follow-up observations were crucial to constraining the orbital motion and hence masses of the two components in the binary system, allowing the team to identify the central body as a black hole roughly 10 times as massive as our sun. To explore the system in more detail, El-Badry and his team turned to the Gemini Multi-Object Spectrograph instrument on Gemini North, which measured the velocity of the companion star as it orbited the black hole and provided precise measurement of its orbital period. Gaia captured the minute irregularities in the star's motion caused by the gravity of an unseen massive object. ![]() The team originally identified the system as potentially hosting a black hole by analyzing data from the European Space Agency's Gaia spacecraft. "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." "I've been searching for dormant black holes for the last four years using a wide range of datasets and methods," said El-Badry. If a black hole is not actively feeding (i.e., it is dormant) it simply blends in with its surroundings. As material from a nearby star spirals in toward the black hole, it becomes superheated and generates powerful X-rays and jets of material. 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. This is the first unambiguous detection of a sun-like star in a wide orbit around a stellar-mass black hole in our galaxy." "While there have been many claimed detections of systems like this, almost all these discoveries have subsequently been refuted. "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 & Smithsonian and the Max Planck Institute for Astronomy, and the lead author of the paper describing this discovery. ![]() 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. This dormant black hole weighs about 10 times the mass of the sun and is located about 1,600 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. ![]() 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.Īstronomers 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 the closest black hole to Earth, which the researchers have dubbed Gaia BH1. ![]()
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