The Hubble Tuning Fork

The gold standard for galaxy classification among professional astronomers is of course the Hubble classification. With a few minor modifications, this classification has stood in place for almost 90 years. A description of the scheme which Hubble calls “a detailed formulation of a preliminary classification presented in an earlier paper” (an observatory circular published in 1922) can be found in his 1926 paper “Extragalactic Nebulae” which is pretty fun to have a look at.

Hubble’s classification is often depicted in a diagram – something which is probably familiar to everyone who has taken an introductory astronomy course. Astronomers call this diagram the “Hubble Tuning Fork”. I have been meaning for a while to make a new version of the Hubble tuning fork based on the type of images which were used in Galaxy Zoo 1 and 2 (OK the prettiest ones I could find – these are not typical at all). Anyway here it is. The Hubble Tuning Fork as seen in colour by the Sloan Digital Sky Survey:

TuningFork

I should say that my choice of galaxies for the sequence owes a lot of credit to an excellent Figure illustrating galaxy morphologies in colour SDSS images which can be found in this article on Galaxy Morphology (arXiV link) written by Ron Buta from Alabama (Figure 48). I strongly recommend that article if you’re looking for a thorough history of galaxy morphology.

Inspired by the “Create a Hubble Tuning Fork Diagram” activity provided by the Las Cumbres Observatory, I also provide below a blank version which you can fill in with your favourite Galaxy Zoo galaxies should you want to. I have to say though, the Las Cumbres version of the activity looks even more fun as they also talk you through how to make your own colour images of the galaxies to put on the diagram.

TuningFork_blank

Anyway I hope you like my new version of the diagram as much as I do. Thanks for reading, Karen.

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About karenlmasters

Astronomer at Institute of Cosmology and Gravitation, University of Portsmouth. Project Scientist for Galaxy Zoo. Also member of Sloan Digital Sky Survey, Dark Energy Survey and Euclid.

4 responses to “The Hubble Tuning Fork”

  1. Karen Masters says :

    And perhaps I should read this blog more closely….! I see Robert (@orbitingfrog) posted about the Hubble tuning fork not so long ago. He even showed a version of the diagram which looks like it uses colour SDSS images. http://blogs.zooniverse.org/galaxyzoo/2010/05/12/types-of-galaxies/

    So I could have saved myself the effort…. I think mine’s prettier though! ;)

    Oh well. Sorry I didn’t read your post Robert. What can I say – too busy doing research with the classifications!

  2. Joseph K. H. Cheng says :

    Very nicely illustrated Hubble tuning fork. Thank you for posting, Karen .

    JKHC.

  3. Alice says :

    I loved this, especially the template! So I made it an Object of the Day http://www.galaxyzooforum.org/index.php?topic=278969.0 :-)

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