Space Warps Talk

What is this????

  • Panaramix by Panaramix

    Odd picture. Can someone tell me what this is???

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  • Capella05 by Capella05 moderator

    Wow, that looks like one amazing merger! I am trying to work out if it is a merger between the top 2 galaxies and the spiral is just an overlap, or if it is between all three 😃

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  • JasonJason by JasonJason

    How can you tell how far away they are without corroborating data as to their distances, isn't that an assumption on your part without more data?

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  • Capella05 by Capella05 moderator

    By analyzing the image, we can see interaction between the upper two galaxies - the 'white haze' between them are tidal waves / star streams. What is more unclear is the spiral galaxy...is it just an overlap? or also in the process of merging? Not possible to answer without access to spectra, with that, I would of been able to give a definitive answer, by comparing the redshift of all the galaxies concerned:)

    Yes, it may be an assumption on my part, but after studying SDSS data (that included a lot spectra!) for more than 5 years, I am able to make an educated comparison between features displayed in this image and other mergers I have studied 😃

    In order not to derail this thread @JasonJason please post your response in a separate thread.

    Apologies @Panaramix. If you have any more questions please let me, or another of the Mods know 😃

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  • Panaramix by Panaramix

    thanks for the response @Capella05

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

    No worries 😃 We are always happy to answer a question 😃

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  • Panaramix by Panaramix

    Well, are these the same galaxies or is this a different one. If it's the same there is no merger, just an overlap.
    same galaxies??

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  • ElisabethB by ElisabethB moderator

    Definitely not the same galaxies but what a gorgeous merger !
    if the galaxies involved show these signs of interaction it is definitely a merger !

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  • Panaramix by Panaramix

    thanks for the respons ElisabethB

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  • drphilmarshall by drphilmarshall scientist, admin in response to JasonJason's comment.

    Thinking a bit about how I know these are nearby galaxies. A lot of the time in extra-galactic astronomy its genuinely hard to tell how far away galaxies are, but we can use the following observation:

    These galaxies are not only bright (which could either be due having a lot of stars, or to being close to us) but also big, compared to other galaxies in the SW images. More distant galaxies all tend to appear to be very roughly the same size as each other, because of the way the expansion of the Universe skews the apparent size of objects, but nearby galaxies always look big.

    I put the last part of my sentence in italics because we nearly always have to make relative measurements in astronomy. Most galaxies you see are distant, just because there is more available volume to contain galaxies at large distances than at short ones. Each field of view contains a square pyramid of space - the further out you look, the more square miles of sky is being contained.

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