Washington: An astronomer has said that all kinds of flat, disk galaxies grow out of their irregular, clumped appearance and their older stars take the same smooth look, while predictably fading from a bright center to a dim edge.
Curtis Struck, a professor of physics and astronomy, Iowa State University, said that a few explanations have been proposed, but most of those only covered certain types of galaxies.
To find out an explanation for the phenomenon, Struck and Bruce Elmegreen , a research scientist at IBM`s Thomas J. Watson Research Center in Yorktown Heights, N.Y., built computer models simulating galaxy evolution.
Struck said that they thought that the clumpy structure of young galaxy disks may be responsible for both its own erasure and the smooth universal brightness profile.
He said that the models showed that`s the case and that the gravity of those clumps of interstellar gases and new stars alter the orbits of nearby stars.
Struck asserted that in some cases, the changes are significant, scattering stars well away from their original and nearly circular orbits and over time, the scattering from circular to slightly elliptical orbits produces the smooth fade in brightness from the center of a galaxy to its edge.
He said that the process takes a few hundred million years to a few billion years.
The findings have been published online by The Astrophysical Journal Letters.