Magazine article Science News

Searching for Evidence of Ringing Galaxies

Magazine article Science News

Searching for Evidence of Ringing Galaxies

Article excerpt

Strike a bell, and it rings. Perturb a galaxy, and it, too, should oscillate. Computer models in which hundreds of thousands of particles attract each other according to the law of gravity indicate that a small disturbance can make these particles move in a coordinated fashion somewhat like the motion of a vibrating bell.

This finding suggests that galaxies, which typically contain billions of stars and large amounts of interstellar gas and dust, may also vibrate in characteristic ways. Such galactic oscillations, if they exist, would probably have originated in the violent processes that led to galaxy formation.

Now, researchers are developing a catalog of effects that astronomers can look for when seeking to determine whether galaxies actually oscillate. Richard H. Miller of the University of Chicago, working with Bruce F. Smith of NASA's Ames Research Center in Mountain View, Calif., and his coworkers, described some of these potentially observable effects at a meeting of the American Astronomical Society's Division on Dynamical Astronomy held last week in Washington, D.C.

The oscillations represent an important, fundamental dynamical process that previously had not been suspected in galaxies, much less taken into account, Miller contends. However, "there's no smoking gun yet to prove they exist." Miller and his colleagues created their simulated galaxies using powerful computers at the Numerical Aerodynamic Simulation Facility at Ames. Their numerical experiments typically involved tracking the behavior of about 400,000 particles distributed in a sphere. …

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