A、It may exist in the neighborhood of big stars. B、It may exist in the neighborhood of a galaxy. C、It may exist at the center of

The existence of black hole had long been predicted by theory but never confirmed.
    A black hole is an extremely mysterious object. It has a gravity which is so intense that nothing, not even light, can escape from it. It can change space and time in basic ways.
    A powerful X-ray stream drew the attention of scientists to the event. It is located near the center of a galaxy which is about 700 million light-years from Earth. According to the international team of scientists, gases from the star have been heated to a temperature of multimillion-degree when they were drawn toward the black hole. Thus a strong wind is produced.
    Scientists said a star about the size of our sun was coming close to the black hole. The big gravity of the black hole pulled the star to the point of breaking. It is estimated to have a gravity 100 million times that of our sun.
    The effect is similar to the dragging force the moon has on the Earth’s oceans, but is much more violent. The black hole has observed to have eaten up about 1 percent of the star. It seems that this unlucky star has just entered the wrong neighborhood.
    Scientists have seen other similar X-ray streams before, but never were able to locate them at the center of a galaxy, where black holes may exist. The new observations also found that a black hole is always surrounded by X-rays.