Galaxy Zoo Talk

Red shifted and classification

  • sandrotassa by sandrotassa

    Hi all,
    I'm not sure how to classify this type of galaxies.
    Any help?


  • karthikeyan.d by karthikeyan.d

    Been having the same dilemma and posted a question in an old thread "Artificially redshifted" but no responses so far. Will retry here.

    For such objects I choose features, no clumps, no bar, no spiral and no bulge. Some times I add "disturbed". Not sure if this is correct but I can't think of another way unless there are clues in these images about the original shapes. I would've classified this also in the same way but the SDSS image shows that it is a smooth one.

    Can anyone from the Science team comment on such objects? Also, any conclusions from the data so far, about the classifications done for these artificially redshifted images?


  • Budgieye by Budgieye moderator

    There is no correct answer. If there is a diversity of opinions, it means that the galaxy is hard to classify, and that is information in itself.

    If I can't see any detail, but I think that it is still a galaxy, I say smooth. Ignore random fluctuations in the image, they are due to simulated distance.

    If it really has faded from sight, I say star/artifact.

    I am just a moderator but this is my interpretation. This study is to find out how galaxies become fuzzy with distance, and how that affects classification. Many spiral galaxies get classified as smooth because they are so far away. I would then think that a bias can be applied to the real data of galaxies out there, so that the number of spirals can be estimated.. Any scientists reading this, feel free to correct or elaborate.

    As for conclusions, you can watch the Blog page after the images are finished, there is often a preliminary result from the scientist. The actual science paper will probably be out in a year after that.

    I have looked back for the old thread "Artifically redshifted" and made a reply. Talk is for us volunteers to chat amount themselves, and moderators try to answer questions, but some slip through. Anyone can answer questions, as long as discussions are polite and scientific. Moderators are mostly here to remove inappropriate comments. 😃


  • karthikeyan.d by karthikeyan.d

    Thanks for the details, in both threads 😃


  • bamford by bamford scientist

    Totally agree with Budgieye. Knowing where we can trust the classifications is as important as the classifications themselves. The fact that we can figure out how uncertain a classification is from the diversity of answers is one of the things that makes Galaxy Zoo more powerful than traditional approaches.

    The artificially redshifted images helped us understand the HST classifications in this paper:

    More work to do science with these classifications is ongoing.