by Zoe Heidenry
Imagine being the first person on earth to ever see a certain galaxy. This happens quite often at Galaxy Zoo. Galaxy Zoo is a project found on the Zooniverse website. Citizen scientists are able to analyze thousands of images taken by the Sloan Digital Sky Survey. My group and I analyzed 20,000 data points taken from the project. Our research question is: “Does the color of a galaxy affect proximity to other galaxies?”
We know that the formation of stars occurs in multiples with the color blue signifying how young a star is. We wanted to see if galaxy formation and spatial distribution will mimic star formation and spatial distribution. We hypothesized that blue galaxies will have a higher local density due to their young age. We tested a variable called local density, which measures how many neighbors a galaxy has nearby. We first filtered the data into red and blue galaxies, then tested the local density of both. We found that red galaxies are more locally dense than blue galaxies. This contradicts our hypothesis, and also answers our question. We could have stopped there, but this finding just created even more questions. We noticed that red galaxies had a really high standard deviation. Standard deviation is the variably of the data set, and explains how close data points were to the average. Basically, the higher the standard deviation, the more varied that data set is. We decided to split the red galaxy data based on two types: Ellipticals galaxies, which are usually old and look like a ball of light, and spiral galaxies, which are usually young and look like their name. We found that red elliptical galaxies had a higher local density than red spiral galaxies. Again, this finding opened up more questions. We knew from previous knowledge that elliptical galaxies vary in size, so we decided to test the local densities of big and small red ellipticals. We used the variable R90_ARCSEC, which is a fancy way of saying size, and found that big red ellipticals have a way higher local density than small red ellipticals. At this point, we wanted to figure out why big red ellipticals have such a high local density. We theorized that since bigger things in space usually have more gravity, big red ellipticals must have a lot of gravity. We think that the big red ellipticals pulled other younger galaxies towards them. An analogy of this would be to think of a city. A city usually starts with one big building, and other new businesses slowly start to build around it.
My team really wanted to focus on communication. One of our goals at the start of this project was to make sure that everyone knew what was happening at all times. Space stuff can often be confusing, so it was essential that everyone understood the research that we were doing. We also wanted to create a safe and open environment for sharing ideas and confusion. I think that we accomplished these goals, because I feel like everyone had a deep understanding of all the graphs and statistics that were created. Our roles were not binary, we didn’t each do one set job. We were all creating graphs and running statistics. At first, this posed a challenge to us because we had so many graphs that we couldn’t quite make sense of them. But, after some discussion, we were able to focus on the parts that we needed, and discarded the excess. We answered our original question pretty quickly, but soon were faced with even more questions — what was so special about red ellipticals? I started running summary statistics (which give the average, range, and median of a data set) on a ton of different variables. I found that size had an affect on local density. I also helped with coming up with our theory of why big red ellipticals might be more locally dense.
Overall, I learned that science is not a linear process. It isn’t easy, and often involves finding something out that creates even more questions than what you started with. My group tested our data until we couldn’t test anymore. We worked well together, and made sure that everyone was on the same page at all times. I started this program with almost zero knowledge about galaxies and star formation. But, after taking the time to sit down and learn about it, I know now that space is not just some foreign and unreachable concept. Anyone can learn about space, regardless of previous education background. I encourage everyone to check out Galaxy Zoo on the Zooniverse, because you never know what discoveries can be made.