Classifying Ring Galaxies

My name is Ciaran O’Hare, I’m a sixth form student at The Cherwell School in Oxford and I came to the Oxford University Astrophysics department as part of my work experience for Year 12. I was set a task to complete of the course of the week, to sort through hundreds of e-mails from from the users of Galaxy Zoo about the unusual ring galaxies.

So I catalogued these galaxies and created catagories, and by finding some data about them we were able to make some interesting discoveries.The ring galaxy is a specific type of galaxy that is believed to be the remnant of a head on collision between a large spiral galaxy and smaller galaxy. One of the most famous is the Cartwheel Galaxy. The first and most common catagory that I made is the circular ring galaxy. These have circular rings and nuclei. Around 54% of the galaxies were of this type.

Typical example –


The second catagory is the elliptical ring galaxies, these have elliptical nuclei and most often, elliptical rings aswell. About 24% of the galaxies were of this type.

Typical example –


The third catagory is the multiple ringed galaxy, where the central nucleus is surrounded by several concentric rings. About 14% of the galaxies were of this type.

Typical example –


The final type is the off centred nucleus. Similar to the first two catagories but the nucleus is not at the centre of the galaxy. This was the rarest catagory it was made up of only 6% of all the galaxies.

Typical example –


An interesting galaxy that a number of users sent in was this, which was the most bizarre one I came across.


I also looked at the spectra of all the galaxies and found that the large majority of them generally fell with the redder galaxies, with only 1 in 8 having bluer spectra. Also, by measuring the radius of the ring we were able to find an age of the galaxy by taking the expansion rate from the cartwheel galaxy. And by comparing this age with the spectra it is clear that the bluer the galaxy is, the younger it is.

These results will now be followed up with more research, and I’d like to thank everyone who e-mailed Galaxy Zoo, for helping in finding these elusive galaxies.

C. O’Hare.

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19 responses to “Classifying Ring Galaxies”

  1. Edd says :

    Ahh – the Scream galaxy at the end!

    Excellent work there. Readers might not be aware of the huge numbers of emails the Zoo got, especially early on, and it’s great that these are getting checked out.

  2. Edd says :

    Whoops – slight mislink to that famous painting. Try here.

  3. fluffyporcupine says :

    Nice work Ciaran!

  4. Hanny says :

    Indeed good to see The Scream here. 😉

  5. Infinity says :

    Great work Ciaran and helpful to see the stats, thanks.

  6. Alice says :

    Hey, how exceptionally cool that Chris got you blogging here, Ciaran. It was great to meet you on Wednesday and I do hope your work experience opened many doors and ideas to you and that you enjoyed it as much as I enjoy my moderating. Thanks for doing that cataloguing and for writing this. All the best!

  7. GwydionM says :

    Great work, Ciaran O’Hare.

  8. Marta Kotarba says :

    Can you give the galaxy ref of this galaxies?

  9. EricFDiaz says :

    Hi Ciaran O’Hare,

    With all due respect, the third image does not look at alllike a true “ring” galaxy but a “ringed” galaxy. The difference being that a “ring” galaxy is the product of a smaller impactor colliding with a much larger spiral. Whereas a “ringed” galaxy is the result of the resonance that occurs at various radii between the galactic bar and the material orbiting in the disk.

    Even though the image is very heavily pixelated, I can tell that the third image is a Type 1 OLR subclass outer pseudoring.

    Classifications: (R1′)SB(r)ab

    I can’t be sure of some of the others because of the poor resolution.

    Best regards,

    Eric F. Diaz

  10. Steven says :

    Hey Ciaran,

    Great work! It sounds like you’ve got some incredibly interesting results there. Amazing for a week’s work! I’m looking forward to seeing the results for myself.

    All the best,

  11. elizabeth siegel says :

    Awesome work. good job

  12. Joseph K. H. Cheng says :

    Claran, you are most welcome. To provide useful data for all astronomical research is the main purpose of the Galaxy Zoo and the aspirations of most if not all the Zooites. Good luck with your interesting research.

  13. Hanny says :

    Just read the whole blog properly, cool! What a job that must have been, looking through all those mails! 😀

  14. EricFDiaz says :

    I agree with Steven, Ciaran. Amazing for a week’s work! And it’s certainly quite interesting to learn the distribution of each type of galaxy that you have listed here. Keep up the great work! 😀

    Best regards,

    Eric F. Diaz

  15. mushroom says :

    Your work experience sounds more interesting than mine (I had to melt 12 ticks into a huge perspex clock face, amongst other things).

  16. Graham dungworth says :

    A superb and fascinating project Ciaran and also to the Cherwell School for the motivation to carry out such research. I wish you every success.

  17. A Mackem says :

    Hi Ciaran. Fantastic work & really interesting results.
    What a great piece of work to do through work experience! Hope you found it inspiring… shows you that maths & stats can lead to some great places eh?
    Good luck with whatever you do in the futrure & pass on thanks to the teachers @school who sorted such a great opportunity.

  18. Jules says :

    Great work Ciaran. A week well spent!

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  1. - July 12, 2008

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