Astronomers around the world were baffled for almost two years by a very powerful flash of light with a strange behavior. A team of researchers may have just found the origin of the phenomenon, which proves to be a rare occurrence of a black hole swallowing a star.
Flashes Of Light In The Sky
Flashes of light are not unusual phenomena at all, astronomers have been aware of their existence for a very long time. As their instruments and knowledge developed, researchers have started to classify these flashes of light according to their origin.
Many of them are caused by supernovae. In such cases, larger stars run out of nuclear fuel and collapse, while their external layers are thrown into space, creating the flashes of light. In other cases, so-called white dwarves "steal" material from neighboring stars and then explode due to the immense weight accumulated.
A Rare Phenomenon
The flash noticed by the astronomers, however, did not seem to fit any of these patterns. First of all, supernovae are usually noticed in newer galaxies, but the mysterious phenomenon was observed in an older one.
Also, in the case of supernovae, the flashes start off by being very intense and then lose energy. The mysterious light fluctuated, losing intensity for a while and then becoming strong again.
As the mystery deepened, a team of researchers composed of postdoctoral fellow Giorgos Leloudas and Prof. Avishay Gal-Yam of the Particle Physics and Astrophysics Department of the Weizmann Institute of Science, as well as Drs. Paul Vreeswijk, Ofer Yaron, Steve Schulze, Joel Johannson, and Ira Bar decided to find the answer.
After having observed and measured the flash of light for more than a year, the team reached the conclusion that the phenomenon is caused by a sun-sized star being swollen by a giant black hole. A phenomenon like this is as impressive as it is rare.
First of all, in order for it to occur, a star should touch a black hole's event horizon so as not to be able to escape its gravitational pull. Second, in order for the flash to occur, light would still need to be able to escape the powerful attraction of the black hole.
This can only happen if the massive black hole spins at a speed that is very close to the speed of light.
"Our data show that the transient rebrightened substantially in the ultraviolet and that the spectrum went through three different spectroscopic phases without ever becoming nebular," quoted the study.
The researchers believe this rare phenomenon will help develop a better understanding of how stars behave when caught in a black hole's gravitational tide.
