New Size Black Hole
By Caty WeaverThis is the VOA Special English SCIENCE REPORT.
Scientists who study space say they have found a black hole that is a different size. Its size is between that of two other known kinds of black holes. The astronomers say the new black hole is bigger than the kind formed when a single star falls in on itself. Yet they say it is smaller than the black holes found at the centers of galaxies.
Black holes are objects of such great mass that nothing can escape their gravity, including light. American astronomers found the new size black hole in a galaxy ten-million light years from Earth. The galaxy is called M-Eighty-Two.
The astronomers discovered the black hole while looking at observations made by an American space agency observatory. The Chandra X-ray Observatory orbits Earth. It took the pictures over a period of several months.
The new black hole is about six-hundred light years from the center of the M-Eighty-Two galaxy. The major sign of its existence is the change in the x-rays produced in the area. The x-rays get stronger as the black hole sucks in gas from nearby stars or clouds.
Small black holes are about the mass of our Sun. Large black holes are one-million to one-thousand-million times greater in mass. This new black hole has a mass at least five-hundred times that of the Sun.
Scientists say there is no physical reason why a middle sized black hole can not exist. But, they are just beginning to question how this size of black hole forms. They say it is too big to be the result of a single star that fell in on itself.
Andrea Preswich [PRESS-witch] is an astronomer with the Harvard-Smithsonian Center for Astrophysics in Massachusetts. She suggests the black hole may have formed by swallowing a number of stars. Or, she says it may be the result of a number of small black holes joined together. However, she says it would be extremely interesting if the new black hole was formed by a single star. She says that would suggest the existence of a star more massive than any known stars.
Other space scientists expressed excitement about what the discovery means for the future. Douglas Richstone of the University of Michigan says he expects more middle size black holes will be found. He says they may help scientists learn about the formation of massive black holes at the centers of galaxies.
This VOA Special English SCIENCE REPORT was written by Caty Weaver.