Archive for September 16, 2013

Professor Helps To Discover Near-Earth Asteroid Is Really A Comet

September 16, 2013 Leave a comment

Some things are not always what they seem—even in space. For thirty years, scientists believed a large near-Earth object was an asteroid. Now, an international team including Joshua Emery, assistant professor of earth and planetary sciences at UT, has discovered it is actually a comet.

Called 3552 Don Quixote, the body is the third largest near-Earth object—mostly rocky bodies, or asteroids, that orbit the Sun in the vicinity of Earth. About 5 percent of near-Earth objects are thought to be “dead” comets that have shed all the water and carbon dioxide in the form of ice that give them their coma—a cloud surrounding the comet nucleus—and tail.

The team found that Don Quixote is neither. It is, in fact, an active comet, thus likely containing water ice and not just rocks. The finding will be presented at the European Planetary Science Congress 2013 in London today, Sept. 10. The discovery could hold implications for the origin of water on Earth.

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Iowa State, IBM Astronomers Explain Why Disk Galaxies Eventually Look Alike

September 16, 2013 Leave a comment

It happens to all kinds of flat, disk galaxies – whether they’re big, little, isolated or crowded in a cluster. They all grow out of their irregular, clumped appearance and their older stars take on the same smooth look, predictably fading from a bright center to a dim edge.

Or, as Curtis Struck, an Iowa State University astronomer, wrote in a research summary: “In galaxy disks, the scars of a rough childhood, and adolescent blemishes, all smooth away with time.”

But how does that happen?

Struck, a professor of physics and astronomy who studies galaxy evolution and wrote the 2011 book “Galaxy Collisions,” said a few explanations have been proposed, but most of those only covered certain types of galaxies. There hasn’t been an explanation for the nearly universal and exponential fade in the brightness of the lookalike disk galaxies.

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