Are Galaxies in Hubble Telescope Photos of Clusters?

[synfiniti]

Below are two URLs to Hubble telescope photos of galaxy clusters.

I would like to know if every single white or colored splotch in these photos is a galaxy, or do single/individual stars/suns manage to get mixed in there?

Thank you for your time.
http://www.jpl.nasa.gov/spaceimages/images/wallpaper/PIA17568-1920x1200.jpg

http://www.jpl.nasa.gov/spaceimages/images/largesize/PIA17569_hires.jpg

 

[Greg Bernhardt]

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.

 

[phyzguy]

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.