Astronomers have discovered a nearby black hole that shreds and consumes a star similar to our sun every time it passes by it, producing a bright X-ray flash.
What is a black hole and how does it eat stars?
A black hole is an object so dense that nothing, not even light, can escape its gravity. Some black holes are formed when massive stars collapse at the end of their lives, while others are supermassive and lurk at the centers of galaxies.Sometimes, a black hole can capture a star that comes too close to it. The star is then pulled by the black hole’s gravity and stretched by the extreme tidal forces. This process is called tidal disruption, and it results in the star losing some of its mass to the black hole.As the star’s material falls into the black hole, it forms a disk around it and heats up to millions of degrees. This disk emits intense radiation, especially in the X-ray range, that can be detected by telescopes.
How did astronomers find the ravenous black hole?
The black hole is located at the center of a galaxy called GSN 069, about 250 million light-years away from Earth. The star orbits the black hole in an elliptical path, and every time it gets close, the black hole rips off some of its material and heats it up to produce a bright X-ray flash. This flash repeats every 25 days, and it was detected by the Neil Gehrels Swift Observatory, a satellite that monitors the sky for X-ray sources.“This is the first time we have seen a star like our sun being repeatedly shredded and consumed by a low-mass black hole,” said Dr. Andrew King, a professor of astrophysics at the University of Leicester and the lead author of the study published in Nature Astronomy. “This event provides a missing link in our knowledge of how black holes disrupt orbiting stars.”The researchers estimate that the black hole consumes about three Earths’-worth of star every time it passes by it, which is equivalent to losing 15% of its mass per year. This means that the star will not survive for more than a few hundred years, and will eventually be completely devoured by the black hole.
Why is this discovery important and what are the implications?
This discovery is important because it shows us how powerful and destructive black holes can be, and how they can affect their surroundings in dramatic ways. It also raises new questions about how common these events are, and what implications they have for our understanding of the cosmos.For example, some scientists think that these events could be a source of gravitational waves, ripples in space-time that are caused by violent phenomena in the universe. Gravitational waves have been detected by instruments such as LIGO and VIRGO from collisions of black holes or neutron stars, but not yet from tidal disruptions.Another question is whether these events could explain some of the mysterious fast radio bursts (FRBs), which are short and intense pulses of radio waves that come from unknown sources in space. Some FRBs repeat periodically, and one possibility is that they are related to stars being eaten by black holes.Finally, this discovery could also help us learn more about how stars evolve and die in different environments, and how black holes grow and influence galaxy formation and evolution.“This is a fascinating phenomenon that we have never seen before,” said Dr. Sara Motta, an astronomer at Harvard University who was not involved in the study. “It shows us how diverse and complex the universe is, and how much more there is to explore.
