[nasional_list] [ppiindia] Scientists find a galaxy joining ours

From: "Ambon" <sea@xxxxxxxxxx>
To: <"Undisclosed-Recipient:;"@freelists.org>
Date: Wed, 11 Jan 2006 02:05:42 +0100
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**http://www.iht.com/articles/2006/01/10/news/galaxy.php


      Scientists find a galaxy joining ours  
      By Warren E. Leary The New York Times

      TUESDAY, JANUARY 10, 2006



     


     
      WASHINGTON A previously unrecognized galaxy appears to be merging with 
the Milky Way, bringing hundreds of thousands of stars into our home galaxy 
that scientists had not noticed until now, astronomers said. 

      A survey of the northern sky has detected a huge, but diffuse structure 
within the confines of the Milky Way that does not seem to fit in with other 
parts of the galaxy that contains our solar system, scientists said Monday. 

      Robert Lupton of Princeton University told a meeting of the American 
Astronomical Society that the large but faint collection of stars rises almost 
perpendicular to the flat, spiral disk of the Milky Way. The most likely 
interpretation of the structure, the astronomer said, is that it is a dwarf 
galaxy that has been merging with our galaxy. 

      The dwarf galaxy lies in the direction of the constellation Virgo at an 
estimated distance of 30,000 light-years from Earth, researchers reported. 

      While some of the stars of the companion galaxy may have been observed 
with telescopes for centuries, they said, no one realized they belonged to 
another body because they are so close and commingled with Milky Way stars. 

      The Milky Way is a flat, pinwheel galaxy measuring more than 100,000 
light-years across and containing an estimated 200 billion stars. A light-year 
is the distance light travels in a vacuum in a year's time, about 9.5 billion 
kilometers, or 5.9 trillion miles. 

      Astronomers found the merging galaxy through the Sloan Digital Sky 
Survey, a project that for more than five years has been mapping the distance 
and characteristics of millions of objects in space. The project is operated by 
a consortium of universities and other institutions. 

      The latest study, which has been submitted to The Astrophysical Journal 
for publication, shows that the Milky Way is still changing and evolving, said 
Mario Juric, a Princeton graduate student who is the principal author of the 
report. "It looks as though the Milky Way is still growing, by cannibalizing 
smaller galaxies that fall into it," he said in a statement. 


      Reporting at the same meeting, another group of researchers said they had 
an explanation for a mysterious warp in the disk of the Milky Way that has 
baffled scientists for decades. 

      Leo Blitz, a professor of astronomy at the University of California, and 
his colleagues Evan Levine and Carl Heiles charted the warp and found evidence 
that it is a ripple or vibration set up by two small galaxies that circle the 
Milky Way. These satellite galaxies, called the Magellanic Clouds, cause 
vibrations at certain frequencies as they pass though the edges of the Milky 
Way, the researchers said. 

      It was previously believed, Blitz said, that the Magellanic Clouds, with 
their combined mass being only 2 percent that of the Milky Way, were too small 
to influence their neighboring galaxy. But when the Milky Way's dark matter is 
taken into account, he said, the motion of the small galaxies can create a wake 
that influences the larger one. 

      Dark matter, invisible material that accounts for most of the universe's 
mass, is 20 times more massive in the Milky Way than all visible material, 
including stars. According to a computer model created with Martin Weinberg, an 
astronomy theorist at the University of Massachusetts at Amherst, dark matter 
spreading from the Milky Way disk with the gas layer can enhance the 
gravitational influence of the Magellanic Clouds as they pass through it. 

     
         


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[nasional_list] [ppiindia] Scientists find a galaxy joining ours

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