Galaxy Zoo Talk


  • Nemesis-of-the-vole by Nemesis-of-the-vole

    The wavelengths (colours) of the two objects look similar which would suggest to me that they were the same distance, but could the off-centre one be a foreground star that is dying and therefore yellow/orange?


  • ElisabethB by ElisabethB moderator

    Hi Nemesis-of-the-vole and welcome to the Zoo

    The central object, which you are supposed to classify is a disk or spiral seen edge on. The object, bottom right, is a foreground star from our galaxy

    Happy hunting ! 😄


  • JeanTate by JeanTate in response to Nemesis-of-the-vole's comment.

    Just to add to ElisabethB's excellent response ... in general, a deep yellow-orange color, in a star or a galaxy, may be an indication of 'old age', but sometimes the image processing goes a bit too far and the colors are artifacts.

    In this image, the star has a funny pink/salmon edge, which is entirely an artifact.

    In galaxies, yellow-orange often signifies not so much 'dying stars' as a lack of young, massive stars (which tend to be blue), which are generally gone within a few (tens of) million years. While some stars in yellow-orange galaxies are indeed 'dying' (they've entered the red giant phase, pretty much a last gasp, before running out of fuel completely), the vast majority may not have even entered middle age.


  • Budgieye by Budgieye moderator

    some reading about colours

    Zooite Guide to SDSS Spectra

    You can judge the distance of galaxies by their colours.
    Colours of Galaxies in SDSS : Redshift chart