Space Warps Talk

Yellow galaxy with blue arms

  • dtrucken by dtrucken

    I'm a lay person, so, be gentle. 😃

    Why would the core of the galaxy be yellow, but the arms blue or even purplish? I tried my only source of understandable (to a mere lay person anyway) knowledge (, and I am now confused even more.


  • Capella05 by Capella05 moderator in response to dtrucken's comment.

    welcome dtrucken 😃

    The different colors have nothing to do with Redshift, as a galaxy (as a whole) shares the same Redshift value.
    In spiral galaxies, the core tends to be made up of older cooler stars - these stars tend to be more yellow / red in color (red = cold). If we have arms with lots of dense star forming regions these tend to be bluer (young star are hot, and hot = blue) so you can see different colors in the same galaxy.

    It would be nicer to see more definition of the arms in the image, but it does account for the color difference. The processing of the images may of slightly distorted the colors, but the science is the same.

    Edited: To correct a typo.