Citizen scientists enlisted to chart galaxies

A study of spiral structure, reduced in complexity so citizen scientists can participate, could offer insight into how galaxies evolve, researchers say. Researchers at the North Carolina Museum on Natural Sciences in Raleigh used software and tracings of known spiral galaxies on paper, and found that no artificial intelligence program, algorithm or other approach was as accurate in depicting the winding-arm design of galaxies. The work, called Spiral Graph, has been described in a paper published in Monthly Notices of the Royal Astronomical Society, and is available to citizen scientists at Zooniverse.org for no charge. "These human-generated tracings give our software a boost so it can accurately measure how tightly wrapped the structure [of the galaxy] is," Patrick Treuthardt of the museum said in a press release. The degree of wrapping of the spiral arms is called the pitch angle -- a spiral with tightly wrapped arms has a small pitch angle, while one with open arms has a large pitch angle. If researchers know the pitch angle, Treuhardt said, they can easily estimate the parameters of other features of galaxies, as well as identify galaxies for follow-up telescope observations.

Spiral galaxies comprise the majority of the galaxies in the nearby universe. In many of these galaxies, the difference in brightness between the winding arms and the inter-arm regions is very subtle, confusing automated approaches of measurement to the point that bright foreground stars can skew an analysis.

Computer algorithms have difficulty determining where spirals begin and end -- but that's not a problem for a human tracing a photograph -- hence the citizen scientist project.

An estimated 6,000 galaxies, of millions, have been graphed thus far, making the project ideal for amateur astronomers.