Disk galaxy NGC 4565 showing its dust lane.
(Credit: University of Minnesota)
Galaxy Zoo 2 is a catalogue of nearby galaxies, collated with the help of more than 83,000 volunteer citizen researchers.
Together with a group of more than 83,000 citizen volunteers from around the world, the University of Minnesota has released Galaxy Zoo 2 — a catalogue of 304,122 nearby galaxies consisting of more than 16 million morphological classifications — that is, classifications based on the galaxies' appearance.
The volunteers began work in 2009, examining images from the Sloan Digital Sky Survey, answering questions about the shape and structure of each galaxy, such as whether it has spiral arms and how many or whether it has galactic bars. Each image is then classified by another 45-50 people in order to achieve more accurate results.
Computers, the researchers said, can be used to classify colour and size, but these finer details are better examined by human eyes.
The resulting catalogue is 10 times larger than any previous catalogue of this kind.
"With today's high-powered telescopes, we are gathering so many new images that astronomers just can't keep up with detailed classifications," said Lucy Fortson, paper co-author and professor of physics and astronomy in the University of Minnesota's College of Science and Engineering. "We could never have produced a data catalogue like this without crowdsourcing help from the public."
The team's work on the next catalogue, however, is already under way. Users can log in to the Galaxy Zoo website to start answering questions about galaxy shapes within seconds. Images of galaxies classified in Galaxy Zoo 2 can be found here.
The paper describing the University of Minnesota's work on Galaxy Zoo 2 can be found online on the Royal Astronomical Society website, titled "Galaxy Zoo 2: detailed morphological classifications for 304,122 galaxies from the Sloan Digital Sky Survey".