Galaxy Zoo Talk

Differences in clumping colors

  • ramberts by ramberts

    Most of the clumps we see are blue and purple it seems in these Hubble images. Is this even an example of a clump? Rarely there are some in this color or turquoise. What do the different colors mean in the clumps? Also a lot of galaxies have rapid color changes I didn't see much in SDSS whereas a galaxy on 2 sides can have 2 entire different colors. What is the significance of that? Sometimes they look like a merger, sometimes they don't.

    Also the picture of examples for more than 4 clumps and I can't tell are just edge-on galaxy bulges, that's an error.

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  • vrooje by vrooje admin, scientist

    The colour can change as a result of many different things, some of which are different physical processes, and some of which are instrumental. These colour images are put together in a very different way from the SDSS images, so the same galaxy might appear to be quite a different colour in the jpg image. Plus, the more distant images in the HST data will appear redder just due to the redshifting by the expansion of the Universe, so an intrinsically blue galaxy might appear quite red to us. In general it's best to not assume a particular feature has to be one colour or another, and to classify regardless of colour.

    Thanks! 😃

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  • Budgieye by Budgieye moderator

    I opened this in Tools, and it has a redshift of 1.1

    I think that is the realm of clumpy galaxies.

    If it were star-forming, I would expect a mixture of blue and red in the object.

    If it is a pea, the the OIII peak would be in the red and there would be little in the blue.

    examples: http://www.galaxyzooforum.org/index.php?topic=277967.msg476366#msg476366 example at z=1.4

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  • ramberts by ramberts

    Thanks for the answers guys. One more question. What is the main difference from star-forming and clumpy regions. Are clumpy regions just bigger than star-forming and typical in younger galaxies and eventually get reduced down to the smaller star-forming region size in time?

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  • Budgieye by Budgieye moderator

    You have now arrived at the frontiers of knowledge, and the results from Galaxy Zoo citizen science will help answer these questions.

    from http://blog.galaxyzoo.org/2010/05/25/a-brief-history-of-clumpy-galaxies/?_ga=1.126327115.711441289.1371287491

    "For example, there appears to be a rough developmental sequence from asymmetric clumpy galaxies, to symmetric clumpy galaxies, to clumpy galaxies dominated by a bright, central clump, and finally to spiral galaxies. Other clumpy galaxies may merge together to form ellipticals. By comparing the numbers and properties of these different types of galaxies we will be able to confirm or refute this picture, and better understand the origins of the galaxy population."

    But notice the words "appears" and "may" and "will" The scientists are still working on the data that was collected by Hubble Zoo in 2010-2011 and making models. Part of this current Zoo started this week, with its clumpy questions, is to refine some of the models.

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  • dj_tjitso by dj_tjitso

    Sorry for going off topic, but what are peas?
    I see them mentioned a lot, but never explained.

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  • Budgieye by Budgieye moderator

    Small round galaxies with extreme rates of star formation. They have lots of large blue stars which live fast and die young, so there are always many supernova explosions, which have hot oxygen which then emits lots of visible light. In SDSS colour filters, these galaxies appear green, so they look like "green peas" . Closer galaxies appear as "blue peas".

    see index for more information

    **3.8 Green compact starburst,Peas ** http://talk.galaxyzoo.org/#/boards/BGZ0000001/discussions/DGZ0000wrb?page=3&comment_id=53d8b93a0d43f77bb6000f98

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  • dj_tjitso by dj_tjitso

    Thanks a lot 😃

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