Are Galaxies in Hubble Telescope Photos of Clusters?

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SUMMARY

The discussion clarifies that in Hubble telescope photos of galaxy clusters, most of the white or colored splotches are indeed galaxies, although some foreground stars from our own galaxy are present. Objects exhibiting four diffraction spikes are identified as stars, caused by light diffraction from the secondary mirror supports. Fainter stars appear as round points, while galaxies may also appear round, making differentiation challenging without spectral analysis. Therefore, while many objects are galaxies, careful observation is required to distinguish them from individual stars.

PREREQUISITES
  • Understanding of Hubble Space Telescope imaging techniques
  • Knowledge of diffraction patterns in optical astronomy
  • Familiarity with galaxy classification and characteristics
  • Basic principles of spectroscopy for astronomical objects
NEXT STEPS
  • Research Hubble Space Telescope imaging techniques and their impact on galaxy observation
  • Study diffraction patterns and their significance in identifying celestial objects
  • Explore galaxy classification systems and their characteristics
  • Learn about spectroscopy and its application in distinguishing stars from galaxies
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Astronomy enthusiasts, astrophysicists, and anyone interested in understanding the complexities of galaxy identification in astronomical imaging.

synfiniti
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Interesting question.

I remember seeing this page
http://hubblesite.org/gallery/album/entire/pr1996001a/

And thinking that if galaxies appear as little white dots, I doubt any single star would show up.
 
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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