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Astronomers detect plasma at black hole
UCLA astronomers report they have detected remarkably stormy conditions in the hot plasma being pulled into the monstrous black hole residing at the centre of our Milky Way galaxy, 26,000 light years away. This detection of the hot plasma is the first in an infrared wavelength, where most of the disturbed plasma’s energy is emitted, and was made using the 10-meter Keck II Telescope at the W.M. Keck Observatory in Hawaii.
“Previous observations at radio and X-ray wavelengths suggested that the black hole is dining on a calm stream of plasma that experiences glitches only 2 percent of the time,” said Andrea Ghez, professor of physics and astronomy at UCLA, who headed the research team. “Our infrared detection shows for the first time that the black hole’s meal is more like the Grand Rapids, in which energetic glitches from shocked gas are occurring almost continually.”
“I see this as a real breakthrough,” said Mark Morris, a UCLA professor of physics and astronomy, who worked with Ghez. “It’s a big leap, not just an incremental advance. The infrared is precisely where we need to look to learn what the black hole is eating. In the infrared, you see it all. The black hole’s dirty laundry is hanging right there for us to see. We’re peering deep down inside this tumultuous region.”
“One of the big mysteries in studies of the black hole at the centre of our galaxy is why the surrounding gas is emitting so little light compared to black holes at the centre of other galaxies,” Ghez said. “We now have a completely new and continuously open window to study the material that is falling onto the black hole at the centre of the Milky Way.”
The astronomers know the location of the black hole so precisely “that it’s like someone in Los Angeles who can identify where someone in Boston is standing to within the width of her hand, if you scale it out to 26,000 light years,” Ghez said. The galactic centre is located due south in the summer sky.
The astronomers are learning what is causing gas to emit radiation as it approaches and enters the black hole. Ghez and her colleagues will continue to study the supermassive black hole at a variety of near infrared wavelengths.
Why Mars is red?
Data from an unmanned Mars probe suggests the red planet’s rusty colour might have come not from water as widely believed but from tiny meteors raining on its surface, a science magazine said.
Scientists exploring the possibility of some form of life existing on Earth’s planetary neighbour are eager to establish whether water exists or has existed on Mars and, if so, in what quantities.
The New Scientist magazine quoted Albert Yen of the US Nasa as saying information from the 1996-97 Pathfinder mission suggested the hue came from meteors and dust containing iron and magnesium.
“If that’s the case, Mars might not have been so wet after all,” the magazine said.
Many scientists have supposed the red colour came from chemical reactions between iron in rocks and now dried-up surface rivers and pools.
The magazine said tests by Yen, of NASA’s Jet Propulsion Laboratory in California, had shown no water was needed to create rust when iron was exposed to ultraviolet light in a chamber containing gases similar to Mars’s atmosphere and at temperatures as low as minus 60 degrees Celsius.
Sound detected from black hole
Nasa’s Chandra X-ray Observatory detected sound waves, for the first time, from a super-massive black hole. The “note” is the deepest ever detected from an object in the universe. The tremendous amounts of energy carried by these sound waves may solve a longstanding problem in astrophysics.
The black hole resides in the Perseus cluster, located 250 million light years from Earth. In 2002, astronomers obtained a deep Chandra observation that shows ripples in the gas filling the cluster. These ripples are evidence for sound waves that have travelled hundreds of thousands of light years away from the cluster’s central black hole.
“The Perseus sound waves are much more than just an interesting form of black hole acoustics,” said Steve Allen, also of the IoA and a co-investigator in the research. “These sound waves may be the key in figuring out how galaxy clusters, the largest structures in the universe, grow,” Allen said.
Sars came from animals
Genetic testing of animals sold as delicacies in a southern Chinese market confirms suspicions that the deadly Sars virus jumped from animals to people, Chinese researchers revealed. The researchers found clear differences between the animal and human versions of the virus, but said they were minor enough to show that Sars jumped from animals, as influenza and other viruses have done.
“It’s a landmark discovery,” said Kathryn Holmes of the University of Colorado Health Sciences Centre, a leading expert on the coronavirus family that Sars belong to.
“The question that everyone has had is, ‘how did this virus appear in the human population?”’ Holmes added in a telephone interview. “This is the first major clue about where the contact might have come from.”
Writing in the journal Science, Yi Guan and colleagues said they found an important clue. The human version of the coronavirus was missing a genetic sequence, a long one, that suggest what changes were needed to make the virus infect humans. — Dawn ScienceDotcom Report
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