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Galaxy cluster photos

  1. May 25, 2015 #1
  2. jcsd
  3. May 26, 2015 #2
  4. May 26, 2015 #3

    phyzguy

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    Some of the objects in these images are foreground stars in our own galaxy, but most are galaxies. For example, in the second image, the objects with the four diffraction spikes on them are almost certainly stars. The diffraction spikes on the brighter objects are caused by light being diffracted by the supports which support the secondary mirror. Fainter star images will be round, since stars are point sources, so anything which is not round is probably a galaxy. However, some galaxies are round, so for the fainter objects, it can be difficult to tell the stars from the galaxies, and a spectrum may be needed to tell for sure.
     
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