Color in Astronomy Research

In this project, you have learned how to quantify color, how to interpret color as resulting from temperature, and how to test your interpretations using color-color diagrams. Now, you are ready to use the SDSS data to do actual astronomy research using colors. As you go through this research, you will be looking at stars and galaxies that no one has ever looked at before.

Research Challenge. Think of a question you would like to answer by studying the colors of objects in the SDSS database. You may use one of the questions below or think of your own.

  • How do the colors of the hottest stars vary? Of the coolest?
  • Can you use a color-color diagram to identify giant or dwarf stars?
  • How do Population I and Population II stars differ? Can you identify any other
    populations of stars from a color-color diagram?
  • Can you distinguish different types of galaxies based on their colors?
  • Can you identify quasars in a field of stars using only their colors?
  • Can you identify different types of quasars based on color?

Once you have identified a question to answer, look at the SDSS database. Find several (at least 20-30) of the objects you are interested in and record their magnitudes. Calculate some or all of the object’s colors (u-g, g-r, r-i, and/or i-z). Make a color- color diagram or examine the spectra of the objects (for those that have spectra available). Make whatever graphs you need to understand your question.