The artist's concept chronicles the star being ripped apart and swallowed by the cosmic beast over time. First, the intact sun-like star (left) ventures too close to the black hole, and its own self-gravity is overwhelmed by the black hole's gravity. The star then stretches apart (middle yellow blob) and eventually breaks into stellar crumbs, some of which swirl into the black hole (cloudy ring at right). This doomed material heats up and radiates light, including ultraviolet light, before disappearing forever into the black hole. The Galaxy Evolution Explorer was able to watch this process unfold by observing changes in ultraviolet light. The area around the black hole appears warped because the gravity of the black hole acts like a lens, twisting and distorting light.

WASHINGTON, Sept. 18 (Xinhua) -- Scientists have found the "missing link" between small and super-massive black holes in a galaxy, according to a study published in Sept. 18 issue of journal Nature.

For the first time researchers from Durham University have discovered that a strong X-ray pulse is emitting from a giant black hole in a galaxy 500 million light years from Earth.

The pulse has been created by gas being sucked by gravity on to the black hole at the center of the REJ1034+396 galaxy.

This composite image shows the jet from a black hole at the center of a galaxy striking the edge of another galaxy, the first time such an interaction has been found. In the image, data from several wavelengths have been combined. X-rays from Chandra (colored purple), optical and ultraviolet (UV) data from Hubble (red and orange), and radio emission from the Very Large Array (VLA) and MERLIN (blue) show how the jet from the main galaxy on the lower left is striking its companion galaxy to the upper right. The jet impacts the companion galaxy at its edge and is then disrupted and deflected, much like how a stream of water from a hose will splay out after hitting a wall at an angle.

X-ray pulses are common among smaller black holes, but the research is the first to identify this activity in a super-massive black hole. Most galaxies, including the Milky Way, are believed to contain super-massive black holes at their centers.

The researchers say their discovery will increase the understanding of how gas behaves before falling on to a black hole as it feeds and develops.

Astronomers have been studying black holes for decades and are able to "see" them due to the fact that gas gets extremely hot and emits X-rays before it is swallowed completely and is lost forever.

The new research found that X-rays are being emitted as a regular signal from the super-massive black hole. The frequency of the pulse is related to the size of the black hole.

This Hubble Space Telescope image, taken December 29, 2005 and released on October 2, 2007 shows giant star-forming nebula with massive young stellar clusters. Astronomers who stumbled upon a powerful burst of radio waves said that they had never seen anything like it before, and it could offer a new way to search for colliding stars or dying black holes.

"Such signals are a well known feature of smaller black holes in our Galaxy when gas is pulled from a companion star," said lead researcher Marek Gierlinski. "The really interesting thing is that we have now established a link between these light-weight black holes and those millions of times as heavy as our Sun."

Scientists hope future research will tell why some super-massive black holes show this behavior while others do not.