Classifying Small Galaxies

Research Question

Small Galaxy

One of many
small galaxies
seen by the SDSS

Galaxies come in two major types: spiral and elliptical. But some galaxies are so small and faint that it’s hard to tell what type they are. How can you classify these small, faint galaxies?

Things you might think about

  1. How do you classify big galaxies when you look at them?
  2. What properties of small galaxies could you measure?
  3. What properties could be different in spirals and ellipticals?
  4. What types of galaxies would you expect to be the brightest? The reddest? The bluest?
  5. What can a galaxy’s spectrum tell you about the galaxy?

Tools that might help you (all links open in new windows)

Navigate: use this tool to get data on single galaxies

Search Form: use this tool to search for data on many galaxies. See the user’s guide to learn how to use the tool.

Image List: use this tool to get thumbnail images of galaxies that meet your search criteria

SQL Search: use the tool below to write complex Structured Query Language (SQL) searches for galaxies

SQL Search


Science background (new windows)

SkyServer galaxies project

Galaxy Zoo (a project where you can classify galaxies)

Galaxy Wikipedia article

SEDS Galaxies (Students for the Exploration and Development of Space)

List of SDSS spectral lines

Hints and cautions (new windows)

If you look at spectra, study the line labels carefully. Not all of them are element names!

You can use SQL aggregate functions (like avg, min, max) to do your analysis.

Look at the data points for “petroR50_g” and “petroR90_r” in the Galaxy table in the Schema Browser. What do those terms mean?


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