DR3 Projects Basic - Scavenger Hunt - The Universe - Asteroids - Types of Stars - Color - Galaxies Advanced Challenges For Kids Games and Contests Links to Others

# Conclusion

Modern astronomers have refined Hubble's classification scheme to include more information about galaxies. However, the modern classification system is still based on the Hubble tuning fork.

Now that you know how to classify galaxies, you are ready to use your knowledge to learn something about what galaxies are like. Below are some ideas for further exploring galaxies in the SDSS data. Choose one, then search through the SDSS data to answer the questions. The Navigation Tool and the SQL Search Tool will help you find galaxies; see the Searching for Data tutorial to learn how to use the SQL Search tool.

When you finish your research project, E-mail us your results, including all your graphs and the object IDs you used to make them. We will look over all the results we receive, and we will put the best of them up on these pages!

 Exercise 5. To prepare for the Research Challenge, make a color-color diagram for a large number of galaxies. Plot u-g on the y-axis and g-r on the x-axis. On your diagram, label each galaxy by its type. Try to identify the areas where different types of galaxies lie on the color-color diagram. Try to come up with rules that will tell you what type of a galaxy you are observing based on its colors. You may want to make other color-color diagrams (such as g-r on the y-axis and r-i on the x-axis) as well.

Research Challenge. The following table contains the redshifts and celestial coordinates of several galaxy clusters. Can you see any differences in the clusters, or the galaxies that make them up, at different redshifts? You may need to make color-color diagrams of several clusters and compare them. Do you notice any differences between rich clusters (with many galaxies) and poor clusters (with few galaxies)?

 Cluster Redshift RA Dec Abell 0023 0.105 5.44 -0.89 Abell 0102 0.0635 12.13 1.43 Abell 0119 0.044 14.09 -1.26 Abell 0189 0.0328 0.91 1.64 Abell 0267 0.230 28.77 1.01 Abell 0370 0.375 39.93 1.54 Abell 0381 0.179 41.48 -0.64 Abell 0919 0.095 151.24 -0.693 Abell 0194 0.0180 21.39 -1.51