By Dan Klepal
The Cincinnati Enquirer

ATHENS - Astronomers at Ohio University have made a discovery that could force scientists to recalculate how much mass - stars, planets and other matter - is in millions of galaxies in the universe.

Using the Chandra X-ray Observatory in orbit above Earth, professors Tom Statler and Brian McNamara identified the largest disk of hot, X-ray emitting gas ever discovered. It's located in galaxy some 160 million light years away.

But the size of the gas disk isn't as important as its rotation. Because the gas has movement - something long theorized but never before proven - it has the potential of throwing off calculations of the amount of cosmic stuff in elliptical galaxies throughout space. The next step, said Mr. Statler, is to see if gas disks in other such galaxies also move.

"The assumption made over the last 20 years is that this gas is at rest, just sitting there in a pressure balance with gravity," Mr. Statler said. "This is one that blows that out of the water. The obvious next question, how widespread is it?

"It could have a long-reaching ramifications in how we measure mass in galaxies and how we picture the histories of galaxies."

At 90,000 light years in diameter, the disk also offers new insights about the way certain galaxies formed and evolve.

"We sort of understand the interplay between stars and interstellar gas, which is important because it's basically where we came from," Mr. Statler said. "Stars are the manufacturing places for two-thirds of what we're made of. We literally owe our existence to it. So if we want to understand our origin and the evolution of the universe, we've got to understand interstellar gas."

E-mail dklepal@enquirer.com