December 5, 2007

Huge Stars Seen as Source of Glowing Gas

Stars in our galaxy may often pump
out waves of million-degree gas that make surrounding nebulas glow with x-rays.

These new findings could shed light into how planetary
systems form—including our own solar system, researchers said.

Astrophysicists focused on the Orion
, a cloud of dense and turbulent gas visible to the naked eye in the
night sky, right below the belt of the constellation Orion. Four extremely bright and massive stars, called the
Trapezium, light up the nebula.

One stretch of the nebula, about 10 light-years wide,
glows with x-rays. This glow apparently results from super-heated gas—some 1.7
million to 2.1 million degree Celsius hot—that pervades the cloud.

Often such vast expanses of
super-heated gas come from exploded stars called supernovas or from large
collections of very massive stars.
Now an international research team using the XMM-Newton space observatory finds
this gas seems to flow from just one bright, young, massive star in the

The Orion Nebula is a
"stellar nursery," where thousands of new stars are being born. There
are many stellar nurseries throughout the Milky Way that, like the Orion
Nebula, only host a few very massive stars. The researchers expect these x-ray
glows occur in many or even all of these nurseries, meaning they "may be
very widespread across the entire galaxy,"
researcher Manuel Gudel, an astrophysicist at the Swiss Federal Institute of
Technology in Zurich, told

"It is now widely believed
that the sun was born in an Orion-like environment," Gudel added.
"Hence, every new piece of information we collect on Orion has
implications on the early history of the solar system, and therefore on our
understanding of our own origins."

The researchers now hope to
understand how these x-ray glows might alter the environments in which
planetary systems form, possibly even influencing the very chemistry of worlds,
Gudel said.

Gudel and his colleagues reported
their findings online Nov. 29 in the journal Science.