Sigmoid and Filament Comparison

Tying into the research we did last summer, we compared the average hydrogen densities, velocities, radial temperatures and alpha to proton ratios of filaments to those of sigmoids in order to see if there are significant differences.

These graphs show the averages of the compositional elements for filaments and sigmoids. Our program breaks a cloud into 8 equal segments and averages the values for each. Then, these averages are weighted based on their calculated errors and they are averaged together to obtain the graphs seen here. We were able to trace 11 clouds back to filaments and 16 clouds back to sigmoids. As you can see, filaments tend to have higher densities throughout the cloud than sigmoids. Sigmoids, on the other hand, tend to have most of their hydrogen density concentrated at the edges of the cloud, with a noticeable drop in density in the 3rd and 4th segments. We checked the profiles of each individual sigmoid event to ensure that the structure we see is not an averaging effect. In fact, this structure is present in at least 10 of the 16 events. In order to further verify this, we plan to examine the composition of the clouds as functions of radius of the magnetic flux rope within the clouds. Hopefully, this will allow us to determine if magnetic pressure is responsible for the density structure seen in sigmoids, as well as allow us to compare the magnetic structure of clouds as functions of their radii. Both sigmoids and filaments appear to have similar velocities, but sigmoids seem to have higher alpha to proton ratios in the beginning of the cloud than filaments do. This could be an indicator that the two have different mechanisms for launching.