First Discovery of a Medium-Mass Black Hole Helps Solve an Astronomical Mystery
Did you know there’s a black hole four billion times the mass of the Sun at the center of our galaxy? Don’t worry, it’s normal. In fact most galaxies have supermassive black holes at their centers, but the details of how they form is a mystery. A black hole recently discovered in our galactic backyard sheds some light on the matter.
Astronomers at the Max Planck Institute led the study which identified a black hole at the center of a cluster of stars called Omega Centauri, only 16,000 light years away. That may sound far, but it’s actually quite nearby on a galactic scale. The team of scientists used 20 years of archived data from the Hubble Space Telescope to track the motion of over one million stars in the cluster. Seven fast-moving stars orbiting close to the center stood out. These stars move so fast that the presence of a central black hole is required to keep the stars gravitationally bound to the cluster. Otherwise, they would fly off into space. Based on the stars’ speeds, the scientists estimated the mass of the black hole to be 8,200 times the mass of the sun. That’s strange for a black hole. Black holes tend to fall neatly into two categories: stellar mass black holes, which are tens of times the mass of the sun, and supermassive black holes, which are hundreds of thousands to billions of times the mass of the sun. Omega Centauri’s black hole fits comfortably into the rare, intermediate mass category, offering a clue as to how supermassive black holes form.
The Omega Centauri stellar cluster is thought to have been plucked from the center of a galaxy some 10 billion years ago, representing a snapshot of an adolescent galaxy containing a seed for a supermassive black hole. Scientists have theorized that midsized black holes like this one may merge to form supermassive black holes, and now there’s evidence. The black hole’s proximity to Earth allows for follow-up studies that will continue to advance our understanding of how supermassive black holes form and evolve.
This study was led by Maximilian Häberle, a PhD student at the Max Planck Institute for Astronomy in Heidelberg, Germany.
Managing Correspondent: Collin Cherubim
Press Article: A middleweight black hole has been spotted for the first time in our galaxy (Science News)
Original Journal Article: Fast-moving stars around an intermediate-mass black hole in ω Centauri (Nature)
Image Credit: AdisResic/Pixabay