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02-23-2005, 06:04 PM
the Space.com website reports that ... (http://www.space.com/scienceastronomy/050223_dark_galaxy.html)
Astronomers have discovered an invisible galaxy that could be the first of many that will help unravel one of the universe's greatest mysteries.
The object appears to be made mostly of "dark matter," material of an unknown nature that can't be seen.
Theorists have long said most of the universe is made of dark matter. Its presence is required to explain the extra gravitational force that is observed to hold regular galaxies together and that also binds large clusters of galaxies.
New Scientist (http://www.newscientist.com/article.ns?id=dn7056) magazine suggests though
Merrifield says that the shortfall in the observed amount of hydrogen may mean that what Minchin and his team have seen is not a dark galaxy after all. "Their story doesn't quite hang together, and I would speculate that they have been fooled by two passing hydrogen clouds." The difference in speed as one passes the other would give the illusion of rotation, he says.
But Minchin is sticking to his guns. "There are so few known hydrogen clouds that to find two together would be extremely unlikely." He thinks they may have underestimated the mass of hydrogen in the dark galaxy. If ultraviolet light from distant quasars were ionising a large proportion of the hydrogen atoms, the gas would be rendered invisible to radio telescopes.
In the meantime, TheSpoof.com reports the headline "Astronomers Find Absolutely Nothing." (http://www.thespoof.com/news/spoof.cfm?headline=s5i7533)
Astronomers have discovered an invisible galaxy that could be the first of many that will help unravel one of the universe's greatest mysteries.
The object appears to be made mostly of "dark matter," material of an unknown nature that can't be seen.
Theorists have long said most of the universe is made of dark matter. Its presence is required to explain the extra gravitational force that is observed to hold regular galaxies together and that also binds large clusters of galaxies.
New Scientist (http://www.newscientist.com/article.ns?id=dn7056) magazine suggests though
Merrifield says that the shortfall in the observed amount of hydrogen may mean that what Minchin and his team have seen is not a dark galaxy after all. "Their story doesn't quite hang together, and I would speculate that they have been fooled by two passing hydrogen clouds." The difference in speed as one passes the other would give the illusion of rotation, he says.
But Minchin is sticking to his guns. "There are so few known hydrogen clouds that to find two together would be extremely unlikely." He thinks they may have underestimated the mass of hydrogen in the dark galaxy. If ultraviolet light from distant quasars were ionising a large proportion of the hydrogen atoms, the gas would be rendered invisible to radio telescopes.
In the meantime, TheSpoof.com reports the headline "Astronomers Find Absolutely Nothing." (http://www.thespoof.com/news/spoof.cfm?headline=s5i7533)
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