* Astronomy

Blobrana · L

Galaxy Zoo

Blobrana · L

Galaxy Zoo 2

Blobrana · L

RE: Galaxy Zoo

Blobrana · L

Title: Galaxy Zoo : Morphologies derived from visual inspection of galaxies from the Sloan Digital Sky Survey
Authors: Chris J. Lintott, Kevin Schawinski, Anze Slosar, Kate Land, Steven Bamford, Daniel Thomas, M. Jordan Raddick, Robert C. Nichol, Alex Szalay, Dan Andreescu, Phil Murray, Jan van den Berg

In order to understand the formation and subsequent evolution of galaxies one must first distinguish between the two main morphological classes of massive systems: spirals and early-type systems. This paper introduces a project, Galaxy Zoo, which provides visual morphological classifications for nearly one million galaxies, extracted from the Sloan Digital Sky Survey (SDSS). This achievement was made possible by inviting the general public to visually inspect and classify these galaxies via the internet. The project has obtained more than 40,000,000 individual classifications made by ~100,000 participants. We discuss the motivation and strategy for this project, and detail how the classifications were performed and processed. We find that Galaxy Zoo results are consistent with those for subsets of SDSS galaxies classified by professional astronomers, thus demonstrating that our data provides a robust morphological catalogue. Obtaining morphologies by direct visual inspection avoids introducing biases associated with proxies for morphology such as colour, concentration or structural parameters. In addition, this catalogue can be used to directly compare SDSS morphologies with older data sets. The colour--magnitude diagrams for each morphological class are shown, and we illustrate how these distributions differ from those inferred using colour alone as a proxy for morphology.

Read more (2389kb, PDF)

Blobrana · L

Title: Galaxy Zoo: The large-scale spin statistics of spiral galaxies in the Sloan Digital Sky Survey
Authors: Kate Land, Anze Slosar, Chris Lintott, Dan Andreescu, Steven Bamford, Phil Murray, Robert Nichol, M.Jordan Raddick, Kevin Schawinski, Alex Szalay, Daniel Thomas, Jan Van den Berg

We re-examine the evidence for a violation of large-scale statistical isotropy in the distribution of projected spin vectors of spiral galaxies. We have a sample of ~ 37,000 spiral galaxies from the Sloan Digital Sky Survey, with their line of sight spin direction confidently classified by members of the public through the online project Galaxy Zoo. After establishing and correcting for a certain level of bias in our handedness results we find the winding sense of the galaxies to be consistent with statistical isotropy. In particular we find no significant dipole signal, and thus no evidence for overall preferred handedness of the Universe. We compare this result to those of other authors and conclude that these may also be affected and explained by a bias effect.

Read more (749kb, PDF)

Blobrana · L

By posting on an Internet forum, Bill Keel set off a research project that will help astronomers learn more about the formation of galaxies and, perhaps, the universe.
Best of all, volunteers in a Web project to classify more than 1 million galaxies performed the research. All the University of Alabama professor had to do was ask the amateur astronomers to send a special sort of image his way.
The armchair astronomers helped Keel find more than 500 images of overlapping galaxies, which happen when a galaxy appears behind another from earths view of the universe. The foreground galaxy is backlit by the formation behind it, making a silhouette of cosmic dust.

Read more

Blobrana · L

You're sitting on a pile of about a million telescopic photos of the universe, and each one needs to be classified. Bit of a job. So what do you do? Astronomers at the University of Portsmouth, Oxford University, and Johns Hopkins University came up with a solution last week that not only alleviated the burden but also generated an enthusiastic response from the public: They opened up the project to volunteers via the Internet.