To make our double bar graph, we will need to know the stellar masses of various galaxies, as well as the type of each of those galaxies (elliptical or spiral).

 

Our procedure follows.

1. Read the data file into the python file.

2. Determine the columns within the data file that contain stellar mass and galaxy type

3. Record the different stellar masses within the data. Do so with a list.

4. For each stellar mass previously recorded, record the number of elliptical galaxies at that mass within a list. The length of this new list should be the same as the length of the list created in step three.

5. Repeat step four, creating a new list and using spiral galaxies, as opposed to elliptical galaxies.

6. Determine an appropriate scale for the horizontal (stellar mass) and vertical (quantity of galaxies) axes.

7. Create the plot within the file.

8. Add the scale determined in step six to the plot created in step seven.

9. Create a dictionary with keys as the elements in the list created in step three and the values as the corresponding elements in the list created in step four.

10. Create a dictionary with keys as the elements in the list created in step three and the values as the corresponding elements in the list created in step five.

11. For each value along the horizontal axis, add a blue bar of a height (along the vertical axis) corresponding to the number of elliptical galaxies possessing the stellar mass at that point on the horizontal axis where the bar lies. This can be done by using the dictionary created in step nine.

12. Repeat step eleven, creating red bars (as opposed to blue bars) corresponding to the quantity and mass of spiral (as opposed to elliptical) galaxies. This can be done by using the dictionary created in step ten.

13.  Label the horizontal axis “Stellar Mass” and add the units; add it to the plot.

14. Label the vertical axis “Quantity of Galaxies”; add it to the plot created in step seven.

15.  Title the plot “Frequency of Stellar Masses in Spiral versus Elliptical Galaxies”.

16.  Create a key for the plot, blue representing elliptical galaxies and red representing spiral galaxies.

17.  Visually determine any correlation between stellar mass and galaxy type.

18. We may encounter challenges with graphing the data: accessing the data, extracting the quantities we need, organizing the extracted information.

We will need to use our communication skills, public speaking skills, and of course, our python skills to be successful as a group in our research project.

We are looking forward to answering our research question, gaining more knowledge regarding galaxies and star formation, and helping contribute to the Galaxy Zoo research project conclusions.