In a groundbreaking discovery, astronomers at the International Gemini Observatory have identified the closest known black hole to Earth.
Located in the constellation of Ophiuchus, the black hole, dubbed Gaia BH1, is about 10 times more massive than the Sun and is located just 1600 light-years away from Earth. The discovery is significant as it is the first unambiguous detection of a dormant stellar-mass black hole in the Milky Way. The close proximity of the black hole offers an opportunity for researchers to gain insights into the evolution of binary systems.
Black holes are among the most extreme objects in the Universe and are known to be incredibly dense. There are thought to be around 100 million stellar-mass black holes in the Milky Way, each weighing between five and 100 times the mass of the Sun. While several of these black holes have been confirmed, almost all of them are “active,” meaning they shine brightly in X-rays as they consume material from a nearby companion star. Dormant black holes, on the other hand, do not emit X-rays and are much harder to detect.
The team made the discovery by analyzing data from the European Space Agency’s Gaia spacecraft, which detected the minute irregularities in the motion of the companion star caused by the gravity of the unseen black hole. Follow-up observations using the Gemini North telescope in Hawaii provided precise measurements of the star’s velocity as it orbited the black hole.
The researchers believe that their findings could have implications for our understanding of the formation and evolution of binary systems. “While 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,” said lead author Kareem El-Badry, an astrophysicist at the Center for Astrophysics | Harvard & Smithsonian. “This is the first time the search has borne fruit, and it offers a unique opportunity to study the evolution of such systems.”
The researchers are now planning to use the Gemini Observatory to search for more dormant black holes in the Milky Way. “It’s exciting to think that there could be many more of these dormant black holes out there waiting to be discovered,” said El-Badry.
“The potential to find them is now much greater, and we plan to continue searching.”
The International Gemini Observatory is operated by a partnership of six countries, including the United States through the National Science Foundation, Canada through the National Research Council of Canada, Chile through the Agencia Nacional de Investigación y Desarrollo, Brazil through the Ministério da Ciência, Tecnologia e Inovações, Argentina through the Ministerio de Ciencia, Tecnología e Innovación, and Korea through the Korea Astronomy and Space Science Institute.
NOIRLab is the preeminent US national center for ground-based, nighttime optical and infrared astronomy. The Association of Universities for Research in Astronomy, Inc. (AURA) operates these facilities and NSF’s NOIRLab under a cooperative agreement with the National Science Foundation (NSF).