27 Apr. (EUROPE PRESS) –
Two massive stars touching in a neighboring galaxy are on their way to becoming black holes that will eventually collide with each other, generating ripples in the fabric of space-time.
The study, conducted by the University College London and the University of Potsdam and accepted for publication in the journal Astronomy & Astrophysicsanalyzed a known binary star – two stars orbiting around a common center of gravity – by analyzing starlight obtained from a variety of ground-based and space-based telescopes.
The researchers found that the stars, located in a neighboring dwarf galaxy called the Small Magellanic Cloud, are in partial contact and exchange material with each other, with one star currently “feeding” off the other. They orbit each other every three days and are the most massive contacting stars (known as contact binaries) observed so far.
Comparing the results of their observations with theoretical models of the evolution of binary stars, they found that, in the best-fit model, the star it is currently feeding on will become a black hole and feed on its companion star. The surviving star will become a black hole soon after.
These black holes will form in just a couple of million years, but then they will orbit each other for billions of years before colliding with such force that they will generate gravitational waves, ripples in the fabric of spacetime, that could theoretically be detected. with instruments on Earth.
PhD student Matthew Rickard (UCL Physics & Astronomy), lead author of the study, said it’s a statement: “Thanks to the Virgo and LIGO gravitational wave detectors, dozens of black hole mergers have been detected in recent years. But so far we have yet to observe stars that are predicted to collapse into black holes of this size and merge into a time scale shorter than or even comparable to the age of the universe.”
Co-author Daniel Pauli, PhD candidate at the University of Potsdam, said: “This binary star is the most massive contact binary observed so far. The smallest, brightest and hottest star, 32 times the mass of the Sun, is currently losing mass in front of its larger companion, which has 55 times the mass of our Sun”.
The black holes that astronomers see merging today formed billions of years ago, when the universe had lower levels of iron and other heavier elements. The proportion of these heavy elements has increased as the universe has aged, making black hole mergers less likely. This is because stars with a higher proportion of heavier elements have stronger winds and break up sooner.
