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Left:
A NASA Hubble Space Telescope image of a randomly selected area of
sky taken to search for faint red stars that might constitute dark matter in
our Milky Way Galaxy. (Dark matter is material of an unknown type that
makes up most of the mass of our galaxy.) If the dark matter in our
galaxy was made of faint red stars -- as many scientists have previously
conjectured -- then about 38 such stars should have been visible in this
HST image. The simulated stars (diamond-shaped symbols), based on
theoretical calculations, illustrate what scientists would have seen if the
dark matter were locked-up in faint red stars.
These surprising results rule out dim stars as an explanation for dark matter
in our galaxy.
Right:
The unmodified HST image shows the region is actually so devoid of stars
that far more distant background galaxies can easily be seen. The field is
in the constellation Eridanus, far outside the plane of our Milky Way
Galaxy. This region was chosen to highlight stars in the galactic halo,
where dark matter exists, and to avoid the contribution of faint stars in the
plane of the galaxy.
Technical Information:
The image was constructed from seven exposures totaling almost three hours of searching by HST. The field shown is about 1.5 arc-minutes across. The image was taken in near-infrared light (814 nm) with the Wide Field Planetary Camera 2, on Feb 8, 1994. This observation is part of the HST parallel observing program.
Credit: J. Bahcall, Institute for Advance Study, Princeton and NASA
Courtesy Space Telescope Science Institute (STScI)
PHOTO RELEASE NO.: STScI-PRC94-41a
© STSCI/NASA
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