Galaxy Zoo Talk

Image AGZ0003ier

  • liometopum by liometopum

    NGC 809
    this is another one of those ringed galaxies that I believe I should classify as a bar with a ring, as per another chat. I looked it up. http://www.atnf.csiro.au/research/conferences/2014/ThePeripheryOfDisks/Talks/Wednesday/POD_Silchenko.pdf calls it an unbarred SO galaxy.

    But what would the moderators want to see for these type of galaxies?

    Posted

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

    Hi @liometopum 😃

    This galaxy does not have a bar, so I would of personally classified it as disk galaxy with a ring. (SO is another name for a disk or lenticular galaxy)

    For future reference, you should classify the galaxy depending on what you see, not how you believe you should classify it.

    Hope I am not repeating what the other mods have been saying, I have not been on the site for the past 3 weeks, so it will take a while for me to catch up.

    Happy hunting! 😃

    Posted

  • liometopum by liometopum

    What tells you it is not an elliptical with a ring?

    Posted

  • Budgieye by Budgieye moderator

    Ellipticals are totally fuzzy, with no internal detail except for a nucleus. I would think that if an elliptical had an apparent ring, it would be a debris trail as result of collision, and the "ring" wouldn't look as symmetrical

    Posted

  • Capella05 by Capella05 moderator

    To follow on from Budgieye, Ellipticals are totally devoid of features:

    Elliptical galaxies are smooth, amorphous systems with a continuously declining brightness distribution and no breaks, inflections, zones, or structures, as well as no sign of a disk.

    Source: GALAXY MORPHOLOGY by Ronald J. Buta, Department of Physics and Astronomy, University of Alabama,

    I highly recommend reading the whole article, and it mentions Galaxy Zoo!

    Posted

  • mlpeck by mlpeck

    Elliptical galaxies are smooth, amorphous systems with a continuously
    declining brightness distribution and no breaks, inflections, zones,
    or structures, as well as no sign of a disk.

    You mean like this?:

    Shell elliptical?

    I'm not sure what series of clicks I would make if I were presented this to classify -- it definitely has features but I'm not sure it's a disk galaxy, and as best as I can remember none of the choices for "anything odd" quite fit. This is NGC 474 by the way. The most popular classification listed in NED is S0.

    According to NED NGC 809 is classified in RC3 as (R)S0+?, which is a lenticular (S0) with an outer ring and some uncertainty about the classification.

    Here is the link to the arxiv version of Buta's monograph for anyone who wants a PDF copy: http://arxiv.org/abs/1102.0550.

    Posted

  • ElisabethB by ElisabethB moderator in response to mlpeck's comment.

    I'd definitely go for features, probably a disturbed spiral or disk with a noticeable bulge. Certainly not smooth, etc.

    Posted

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

    In that example I would say it has zones, breaks and structures!

    If I was classifying the image I would go for: Features or Disk --> Not a edge on -->No bars / spiral arms etc --> yes, there is something odd -->other.

    But that is just me, others are perfectly entitled (and encouraged) to disagree 😃 That is why we have multiple classifications!

    Edited to add: I do know what you mean, the classification structure is quite limited with the choices you can make, but I think that is intentional.

    Posted

  • liometopum by liometopum

    That galaxy image looks a lot like "Shell Galaxy NGC 1344"
    http://www.astrodonimaging.com/gallery/display.cfm?imgID=268

    That page states "NGC 1344 is an apparently normal elliptical galaxy "

    Posted