It survived a close encounter with a giant black hole, mass 400,000 times the Sun, in the center of the galaxy GSN 069, about 250 million light years from Earth. It is a red giant, a star like the Sun in the final phase of its evolution which, having exhausted its nuclear fuel, begins to swell.
Astronomers from the British University of Leicester, coordinated by Andrew King, noticed his presence thanks to a regular x-ray emission like a clock, every nine hours. The phenomenon is described in the study published in the Monthly Notices of the Royal Astronomical Society.
The radiation from the star that ended up in the jaws of the black hole was captured by NASA's Chandra X-ray space telescopes, and the European Space Agency (ESA) Xmm-Newton. Meetings like this, astronomers explain, can help better understand how a black hole grows.
As the star approaches the black hole, astronomers explain, it loses the outermost layers due to the frightening gravitational pull of this cosmic vacuum cleaner. However, she manages to survive, coming out of this close encounter as naked, in the form of a white dwarf, a star slightly larger than Earth.
"It remains, however, harnessed, orbiting the black hole every nine hours," explains King. In each of these orbits, the white dwarf loses some of its mass, continuing to feed the black hole. The phenomenon is accompanied by an intense emission of X-rays, captured by the two telescopes of NASA and ESA. Experts predict that the star, still orbiting a safe distance from the black hole, could remain in its grip for billions of years.