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Monday 25th April, 2011
Universe is twice as bright as previously thought
Big News Network.com (ANI) Friday 16th May, 2008
London, May 16 : Astronomers from UK Universities working with
colleagues from Germany and Australia have calculated that the Universe
is actually twice as bright as previously thought.
The team of
astronomers has come up with this theory after finding how dust is
obscuring approximately half of the light that the Universe is currently
generating.
"For nearly two decades we've argued about whether
the light that we see from distant galaxies tells the whole story or
not," said lead author Dr Simon Driver from the University of St
Andrews.
"It doesn't; in fact only half the energy produced by
stars actually reaches our telescopes directly, the rest is blocked by
dust grains," he added.
While astronomers have known for some
time that the Universe contains small grains of dust, they had not
realised the extent to which this is restricting the amount of light
that we can see. The dust absorbs starlight and re-emits it, making it
glow.
They knew that existing models were flawed, because the
energy output from glowing dust appeared to be greater than the total
energy produced by the stars.
"You can't get more energy out than
you put in so we knew something was very wrong. Even so, the scale of
the dust problem has come as a shock appears that galaxies generate
twice as much starlight as previously thought," said Dr Driver.
For
their research, the team combined an innovative new model of the dust
distribution in galaxies developed by Dr Cristina Popescu of the
University of Central Lancashire and Prof Richard Tuffs of the Max Plank
Institute for Nuclear Physics.
Using the new model, the astronomers could calculate precisely the fraction of starlight blocked by the dust.
"The
results demonstrate very clearly that interstellar dust grains have a
devastating effect on our measurements of the energy output from even
nearby galaxies," said Professor Richard Tuffs. "With the new calibrated
model in hand, we can now calculate precisely the fraction of starlight
blocked by the dust," he added.
After carefully measuring the
brightness of thousands of disc-shaped galaxies with different
orientations, the astronomers matched their observations to computer
models of dusty galaxies.
From this, they were able to calibrate
the models and, for the first time, determine how much light is
obscured when a galaxy has a face-on orientation. This then allowed them
to determine the absolute fraction of light that escapes in each
direction from a galaxy.
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Since being uprooted from their lands in 1948 to make way for
Israel, Palestinians have been struggling to attain statehood. In
September the UN General Assembly will be asked to declare a Palestinian
state. The U.S. and Israel are working hard to ensure that doesn't
happen.
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