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"Dark Galaxy" found.

Discussion in 'News' started by The Leader, Feb 24, 2005.

  1. The Leader

    The Leader 12oz Senior Member

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    "Dark Galaxy" found.

    Discussion started by The Leader - Feb 24, 2005

    Strong evidence for a massive galaxy totally devoid of stars has been found in the Virgo cluster, about 50 million light years away from Earth. If the existence of this "dark galaxy" is confirmed, it will vindicate the favoured theory of how galaxies form - and will present fresh puzzles to solve.

    The new galaxy, which consists of a gigantic cloud of hydrogen gas and exotic dark matter, contains enough material to give birth to tens of millions of stars. Yet something is preventing this from happening. Such dark galaxies have been predicted, and could outnumber normal galaxies by as much as a hundred to one, but this is the first time anyone has confidently claimed to have seen one.

    The discovery should come as a relief to astrophysicists developing theories of how galaxies form. "If there are no dark galaxies in the universe, then we must be missing an important piece of physics," says Michael Merrifield at the University of Nottingham, UK.

    For decades computer simulations have consistently predicted far more small galaxies than have been observed. For example, in our local group of galaxies there should be hundreds of dwarf galaxies, along with the gigantic Milky Way and Andromeda galaxies. Yet only 35 dwarf galaxies have been observed.

    One possibility is that these dwarfs exist as dark galaxies - starless clouds of hydrogen and dark matter. "The search for dark galaxies is crucial because there is a major disagreement between the theory of galaxy formation and observation," says Riccardo Giovanelli at Cornell University in Ithaca, New York, US.
    Cosmic stone's throw

    The theorists took heart in 2005 with the announcement that the dwarf galaxy I Zwicky 18, situated just a cosmic stone's throw from the Milky Way in a region where other galaxies are billions of years older, contained no stars older than 500,000 years (New Scientist print edition, 11 December 2004). Either the galaxy formed recently, or it has been hanging around as a dark galaxy for as long as 13 billion years.

    Apart from such tantalising but inconclusive findings, no evidence has turned up until now. The most recent failure was 2004's HIPASS survey, which used the 64-metre Parkes radio telescope in New South Wales, Australia.

    By definition, dark galaxies cannot be seen by optical telescopes. The only signs are radio waves with wavelengths of about 21 centimetres emitted by the hydrogen atoms that make up most of the gas in galaxies. Giovanelli says that HIPASS failed to find any dark galaxies because it was not sensitive enough.

    In the latest survey, an international team led by Robert Minchin at Cardiff University, UK, used the sensitive 76-metre Lovell radio telescope at the University of Manchester's Jodrell Bank Observatory, UK, to look for dark galaxies in the nearby Virgo cluster. There they found VIRGOHI21, a rotating cloud containing enough hydrogen gas to spawn 100 million stars like the sun and fill a small galaxy.

    All previous possible dark galaxies have turned out to be duds: observations made using high-powered optical telescopes showed they contained stars after all. But when Minchin and his team used the 2.5-metre Isaac Newton optical telescope on the island of La Palma, Spain, they found no stars. "This is the first object we can be confident is a dark galaxy," Minchin says.
    Speed of rotation

    But far from answering all the questions, VIRGOHI21 is throwing up a number of new ones. One concerns its mass. While the newly discovered galaxy is certainly dark, it may not be the dwarf that astrophysicists were hoping for.

    If galaxies were made up only of ordinary matter, their speed of rotation would tear them apart. The extra mass needed to provide the gravitational pull that holds them together is generally thought to come from what is called dark matter.

    When Minchin's team measured the speed of rotation of the hydrogen gas in VIRGOHI21, they found that it would have to contain about one-tenth of the dark matter of the Milky Way. But if that is so, it should also have a hundred times as much hydrogen gas as they actually detected. Far from being a dwarf, VIRGOHI21 seems to be a giant in its own right.

    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.



    http://www.newscientist.com/article.ns?id=dn7056
     
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  2. ledzep

    ledzep 12oz Junior Member

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    ledzep - Replied Feb 24, 2005

    man I wanna read that real bad, but I gotta go.
     
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  3. boogie hands

    boogie hands 12oz Legend

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    boogie hands - Replied Feb 24, 2005

    this is probably the best thing ive seen on 12oz in the past year.....thanks.
     
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  4. 2 blaazed

    2 blaazed New Jack

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    2 blaazed - Replied Feb 24, 2005

    good read
     
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  5. The Leader

    The Leader 12oz Senior Member

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    The Leader - Replied Feb 25, 2005

    You people have got to be kidding me. This the fucking universe, much bigger than what Bush is doing. CHECK THIS SHIT OUT.
     
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  6. emergin_graffer

    emergin_graffer 12oz Junior Member

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    emergin_graffer - Replied Feb 26, 2005

    good post. interesting info. :mexican:
     
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  7. CamAlmighty

    CamAlmighty 12oz Senior Member

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    CamAlmighty - Replied Mar 2, 2005

    Sounds funky.
     
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  8. Æ°

    Æ° 12oz Senior Member

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    Æ° - Replied Mar 7, 2005

    More interesting news in the world of matter:

    GENEVA - Installation of the world's largest particle physics collider began Monday with the lowering of a massive, superconducting magnet into the circular tunnel housing the new research facility that will draw scientists from all over the world, a spokeswoman said.

    The 17-mile tunnel, housing the pipe-like accelerator, is big enough for a subway train and is located 150 to 500 feet under the Swiss-French border.

    The aim of the project is to make the particles — in this case protons — travel at nearly the speed of light until they collide, emitting a shower of even smaller particles that will reveal mysteries about the makeup of matter.

    The 50-foot-long magnet is the first of 1,232 of the same size that will be placed in the tunnel to speed subatomic particles around the accelerator, said Renilde Vanden Broeck, spokeswoman for the European Organization for Nuclear Research, known by the French initials CERN (news - web sites ).

    Italian Professor Lucio Rossi, who heads the magnet and superconductor project, said work had fallen four to six months behind because of technical problems in building and installing the huge magnets.

    "Now we are catching up," Rossi told The Associated Press, adding that he hopes "to finish exactly on time" so that the collider can start on schedule at the end of 2007.

    The magnet that was lowered Monday weighs more than 38 tons. There will also be hundreds of other, smaller magnets in the tunnel.

    The $1.8 billion accelerator, to be known as the Large Hadron Collider, will replace an earlier, less-powerful model that was removed from the tunnel in 2000.

    Vanden Broeck said the magnets will be cooled to minus-456 degrees Fahrenheit so they can convey extremely high currents without any loss of energy.

    That will enable them to control the path of the protons, which are 2,000 times heavier than the much more easily directed electrons that were used in the earlier accelerator.

    The superconducting magnets, chilled by super fluid helium, are a first for CERN, which previously used conventional magnets.

    Similar superconducting magnets are in use at the Fermilab outside Chicago, which is currently the world's most powerful collider, Rossi said. But the CERN magnets will have almost double Fermilab's magnetic field and the CERN accelerator is several times larger.

    "It makes our accelerator approximately eight to 10 times more powerful than the one that is in Batavia, Illinois," Rossi said.

    After the U.S. Congress in 1993 halted construction on the proposed Superconducting Super Collider in Texas, CERN became a focus for world research into matter and into understanding the origins of the universe.

    Many American scientists are among the 6,500 scientists from 80 countries — half the world's researchers specializing in particle physics — who work at CERN.

    The lab's 20 European member countries, as well as observer states like the United States and Japan, make contributions to pay CERN's yearly budget of about $800 million.

    Rossi said he was delighted to be able to proceed with the installation. The delay has left CERN with a massive backlog of equipment — 800 huge magnets that had to be stored outside because there were no buildings large enough to warehouse them.
     
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  9. Æ°

    Æ° 12oz Senior Member

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    Æ° - Replied Mar 7, 2005

    I'd also like to add if you find space, planets, and the whole question of existence fascinating I'd like to recommend a few documentaries. All of these are available on eMule and they have forever changed the way I look at things.

    The Elegant Universe
    Stephen Hawking's Universe (6 part series)
    BBC Earth Story (8 part series)

    Watch all 3 back to back for the full effect and you will spend the following weeks daydreaming about space and time every second you're awake.
     
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  10. imported_El Mamerro - Replied Mar 7, 2005

    Read the book instead if you have the chance. Lots more stuff in there than what made it into TV.
     
  11. Æ°

    Æ° 12oz Senior Member

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    Æ° - Replied Mar 7, 2005

    Slick, I didn't even know it was a book.
     
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  12. AORAone

    AORAone 12oz Veteran Member

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    AORAone - Replied Mar 17, 2005

    this is pretty fuckin badass, definitly worth the read. i just wish i knew what some of the terms meant so i could understand a little more of what they're talking about. dope thread tho.
     
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  13. The Leader

    The Leader 12oz Senior Member

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    The Leader - Replied Mar 18, 2005

    Yess. This thread is still lurking.
     
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  14. willy.wonka

    willy.wonka Guest

    willy.wonka - Replied Mar 21, 2005

    its a dope thread.
     
  15. caffeine

    caffeine 12oz Member

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    caffeine - Replied Mar 21, 2005

    It fascinates me how recent the discovery of dark matter and its implications are. Its crazy to think that despite how emersly large our universe continues to expand, that theres something we cant even measure, called dark matter, taking up almost half of its entirity. Great topic.
     
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