Home Tags Chandra x ray
Tag: chandra x ray
Lobes of unexpectedly hot gas speeding away from a black hole in our galaxy have been discovered with NASA 's Chandra X-ray Observatory. The high temperature and the distance of the lobes from the black hole indicate that violent collisions are occurring between clumps of gas expelled from the vicinity of the black hole. A key finding was evidence indicating rapidly moving hot iron atoms. "Just like a super-highway, it's a dangerous world out there," said Simone Migliari on the University of Amsterdam, lead author on a paper from a September 6, 2002 issue of Science magazine. "Blobs of gas are getting rear-ended at speeds in excess of a hundred million miles per hours!"
This image from the Chandra X-ray Observatory has given scientists their first look at X-rays from Mars. In the sparse upper atmosphere of Mars, about 75 miles above its surface, the observed X-rays are produced by fluorescent radiation from oxygen atoms. X-rays from the Sun impact oxygen atoms, knock electrons out of the inner parts of their electron clouds, and excite the atoms to a higher energy level in the process. The atoms almost immediately return to their lower energy state and may emit a fluorescent X-ray in this process with an energy characteristic of the atom involved ? oxygen in this case. A similar process involving ultraviolet light produces the visible light from fluorescent lamps.
New evidence from NASA's Chandra X-ray Observatory challenges an alternative theory of gravity that eliminates the need for dark matter. The observation also narrows the field for competing forms of dark matter, the elusive material thought to be the dominant form of matter in the universe. An observation of the galaxy NGC 720 shows it is enveloped in a slightly flattened, or ellipsoidal cloud of hot gas that has an orientation different from that of the optical image of the galaxy. The flattening is too large to be explained by theories in which stars and gas are assumed to contain most of the mass in the galaxy. "The shape and orientation of the hot gas cloud require it to be confined by an egg-shaped dark matter halo," said a researcher involved in the stoudy. "This means that dark matter is not just an illusion due to a shortcoming of the standard theory of gravity ? it is real."
12Page 2 of 2