A new study has revealed the possible existence of several black holes in the Hyades star cluster, the closest cluster of stars to our solar system. These black holes would be the nearest ones to Earth ever detected, and could shed light on the formation and evolution of these mysterious cosmic objects.
What are black holes and how are they detected?
Black holes are regions of space where gravity is so strong that nothing, not even light, can escape. They are formed when massive stars collapse at the end of their life cycle, or when two smaller black holes merge. Black holes are invisible, but they can be detected by their effects on the surrounding matter and radiation. For example, when two black holes collide, they produce gravitational waves that ripple through space-time and can be measured by sensitive detectors on Earth.
How did the researchers find black holes in the Hyades cluster?
The Hyades cluster is a group of about 400 stars that are located about 150 light-years away from us. It is the closest open cluster to our solar system, and has been known since ancient times. The researchers used simulations that tracked the motion and evolution of all the stars in the Hyades cluster, and compared them with the actual positions and velocities of the stars measured by the Gaia satellite. Gaia is a European Space Agency mission that is creating a three-dimensional map of our galaxy, with unprecedented accuracy and detail.
The researchers found that their simulations could only match the observed properties of the Hyades cluster if some black holes were present at the center of the cluster today, or until recently. They estimated that there could be two or three black holes in the Hyades cluster right now, or that all the black holes have been ejected from the cluster less than 150 million years ago. In either case, these black holes would be much closer to us than any other known black hole, which is about 480 light-years away.
Why is this discovery important?
This discovery is important because it could help us understand how black holes form and interact with their environment. The Hyades cluster is relatively young, about 600 million years old, and has a similar age and chemical composition to our sun. Therefore, studying its black holes could reveal how our sun and its siblings were born and evolved. Moreover, finding black holes in open clusters could have implications for the detection of gravitational waves from merging black holes. Open clusters are loosely bound groups of stars that can easily lose their members due to gravitational interactions with other stars or galaxies. Therefore, finding black holes in open clusters could indicate that there are more isolated black holes in our galaxy than previously thought, and that they could merge more frequently than expected.
The researchers plan to continue their investigation of the Hyades cluster and its potential black holes, using more data from Gaia and other telescopes. They also hope to apply their method to other open clusters in our galaxy, and search for more hidden black holes in our cosmic neighborhood.