Science & Technology Editor
Washington (UPI) Mar 03, 2005
Science has come a long way since the days of the clockwork universe, when the stars of the night sky remained fixed in their positions and the objects the Greeks called planets, or "wanderers," followed precise and simple paths across the heavens.
Now, after Einstein and Hawking and a host of others whose minds have probed the nature of the cosmos have weighed in, we continually find it to be an increasingly unpredictable and astounding place.
The latest cause for oohs and ahs involves the processes required to turn gigantic and loose agglomerations of dust into compact and highly energetic bodies that anchor solar systems.
A team of astronomers, using the European Space Agency's XMM-Newton orbiting telescope, has spied a distant star hatchery and found the earliest and most detailed view of a collapsing gas cloud - an event analogous to taking the first ultrasound of a fetus growing inside a womb. Even without the accompanying mystery, it is a spectacular feat.
"We are seeing star formation at its embryonic stage," said Kenji Hamaguchi, with NASA's Goddard Space Flight Center in Greenbelt, Md., lead author of a report about the discovery appearing in The Astrophysical Journal. "Previous observations have captured the shape of such gas clouds, but have never been able to peer inside."
The mystery is that some unknown, perhaps electromagnetic process is superheating the cloud and actually helping it condense.
The research team knows the cloud is superheating because it is emitting high-energy particles in the form of X-rays. The cloud is not a star yet, however. Rather, scientists call it a Class 0 protostar - a category that is far earlier in a star's evolution than they rightly would have thought possible to observe.
They know some mysterious force is at work because the X-rays mean the dust is condensing toward the protostar's core - and generating the superheating - about 10 times faster than possible if just gravity was supplying the attraction.
"The detection of X-rays this early indicates that gravity alone is not the only force shaping young stars," Hamaguchi said.
That is indeed what seems to be happening. The research team used supporting data from NASA's orbiting Chandra X-ray observatory, Japan's Subaru telescope in Hawaii, and the University of Hawaii's 88-inch telescope.
They confirmed X-rays were emanating from the protostar, located in a star-forming area called R Corona Australis, about 500 light-years from Earth.
A class 0 protostar is the youngest - very much analogous to a fetus in its first trimester - only about 10,000 years to 100,000 years old.
Normally, a stellar cloud's temperat ure would be about minus 400 degrees Fahrenheit (minus 240 degrees Celsius), or very close to absolute zero. It requires a few million years of condensation and compression before nuclear fusion finally kicks in and ignites at the center of the cloud - and a star is born.
In the case of this object, however, somehow magnetic fields in the spinning protostar's core are accelerating the accumulating matter to high speeds, producing superheating and generating X-rays.
"This is no gentle freefall of gas," said Michael Corcoran, also with Goddard and co-author of the research.
"The X-ray emission shows that forces appear to be accelerating matter to high speeds, heating regions of this cold gas cloud to 100 million degrees Fahrenheit."
Because of all that energy, astronomers actually can use the X-rays to probe inside the cloud - the process really does resemble a fetal ultrasound.
"The X-ray emission from the core gives us a window to probe the hidden processes by which cold gas clouds collapse to stars," Corcoran said.
Hamaguchi said the protostar probably was generating X-rays in the same way solar flares do on the surface of the sun. That hot solar surface generates lots of magnetic loops, which sometimes get tangled and release large amounts of energy - enough to accelerate matter to velocities of about 7 million miles per hour.
When particles smash against the solar surface, they create X-rays. Hamaguchi's team thinks tangled magnetic fields caused by static electricity within the protostellar cloud might be generating X-rays.
The existence of magnetic fields in a very young protostar had led the team to think magnetic loops play a critical role in shepherding the cloud's condensation.
They used the ESA's XMM-Newton telescope for its sensitivity, because few X-rays actually can escape the dusty region. They used Chan dra's resolving power to pinpoint the X-ray source, and the infrared Subaru telescope to determine the protostar's age.
"The age is based on a well-established chart of spectra, or characteristics of the infrared light, as the protostar evolves over the course of a million years," said Ko Nedachi, a doctoral student at the University of Tokyo who led the Subaru observation.
With their findings, Hamaguchi's team has raised the star-forming process an octave in complexity and given yet another reason to behold the night sky with amazement and humility.
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Champaign IL (SPX) Mar 03, 2005
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