May 10, 2005 — Gigantic X-ray explosions from the sun in its rowdy youth may be responsible for the existence of planet Earth.

New observations of X-ray blasts from young stars in the Orion Nebula have revealed a couple of dozen younger siblings of our own sun, half of which have possible disks of planet-building material orbiting around them.

Flares from those stars, a thousand times more powerful than our sun's solar flares, may be causing turbulence in the dusty, proto-planetary disks that keeps young planets from spiraling into the stars.

"What we did was to use the Orion nebula cluster as a virtual time machine," said astrophysicist Scott Wolk of the Harvard-Smithsonian Center for Astrophysics.

About 4.5 billion years ago, our sun was very much like those in the Orion Nebula, he said. In fact our solar system was probably born in a place very like the Orion Nebula.

By watching the sun-like stars in the nebula for 13 days with the orbiting Chandra X-Ray Observatory, a team of more than three dozen researchers around the world were able to see 41 huge X-ray bursts from the stars, signaling violent magnetic storms.

The results of what is called the Chandra Orion Ultradeep Project will be featured in the October 2005 supplement of Astrophysical Journal.

The magnetic stellar storms that created the X-ray explosions are important, said Eric Feigelson, professor of astronomy and astrophysics at Pennsylvania State University.

They're large enough to heat the disks of "proto-planetary" material — which likely contain clumps that could become the cores of future planets — and give it an electric charge.

This charge, combined with motion of the disk and the effects of magnetic fields, creates a jostling that's potentially important for planet formation.

"It buys time for planetary cores," said astronomer Joan Najita of National Optical Astronomy Observatory. "In a turbulent disk, planetary cores execute a random walk, which increases the time they take to spiral in."

Time enough for them to become planets like Earth and reach a point in the solar system's history when there is less material floating around and slowing planets down, she explained.

Without the turbulence, planetary cores would theoretically be slowed by the clouds of dust and gas until they spiraled into their suns in just a million years.

But the Orion Nebula gang of sun-like youths is showing that over time, the proto-planetary disks are being exposed to literally tens of millions of massive blasts, plenty of jostling to keep any proto-planets clear of danger.

"When solar flares are emitted from the sun today, we think of them as a nuisance," said Najita. "But when emitted by the sun in its youth, they could have played an important role in (the solar system's) development."

The Orion Nebula is 1,500 light-years away and can be seen with the naked eye as a fuzzy patch in Orion's sword.