StarBulletin.com

Fireballs seen shooting off galaxies


By

POSTED: Tuesday, October 07, 2008

Astronomers using the Subaru Telescope at the summit of Mauna Kea have discovered truly enormous blobs of superheated gas that they describe as “;fireballs.”;

The blobs are 3,000 to 6,000 light-years across. In comparison, the distance from our sun to the nearest star is just 4.3 light-years.

The fireballs have a mass 10 million times as great as the sun, a Subaru news release said.

And the fireballs are hot, tens of millions of degrees at the time they start to form. That is much hotter than the hottest visible part of the sun, the million-degree corona, seen only during a total eclipse.

These were some of the findings revealed yesterday in Japan by an astronomy team led by Michitoshi Yoshida of the Okayama Astrophysical Observatory. The findings will be published in the Dec. 10 issue of Astrophysical Journal.

Yoshida's team discovered the fireballs in 2006 and 2007 while looking at a particular galaxy in a group of galaxies 300 million light-years away called the Coma Cluster.

The galaxy called RB199 was shooting out threads of hot gas as much as 260,000 light-years long. Forming knots on these strands were the fireballs, and inside them, stars were forming.

Seeing these weird fireballs on strings of gas was easier than figuring out how they formed.

After weighing various ideas, Yoshida's team finally decided the cause was “;ram pressure stripping.”;

The Coma Cluster is a pretty cluttered place, with about 1,000 galaxies zipping around, crashing into each other, plowing through hot gas.

RB199 is speeding through a patch of gas at 1,200 miles per second, the Subaru statement said. In comparison, the earth taking its annual spin around the sun dawdles along at a mere 18.5 miles per second.

Speed demon RB199 rams enough gas and creates enough pressure to make the long strings with fireballs shoot off into space, Yoshida's team concluded.

Yoshida hinted that his teams would like to understand the process a lot better. “;The team is confident that our study of these phenomena leads to a better understanding of the gas stripping process in galaxy clusters, and the effect of clusters on the evolution of individual galaxies,”; he said.