New theory: Gamma-ray blast spawned planets

Supernova 1997ce, as imaged by the Hubble Space Telescope. Two Irish astrophysicists believe gamma rays emitted by the an explosion like this one may have been a catalyst for planet formation in our solar system.

September 10, 1999
Web posted at: 4:50 p.m. EDT (2050 GMT)

(CNN) -- A violent blast of gamma-rays may have sparked the formation of our solar system's rocky planets within minutes, two Irish astrophysicists say.

The flood of energy melted primordial dust grains, seeded the formation of meteorites and helped Earth and the other rocky planets coalesce quickly from a disc of gas and dust, say Brian McBreen and Lorraine Hanlon of University College Dublin.

Pre-planetary beads, called chondrules, likely formed in a matter of minutes 4.5 billion years ago when the radiation burst seared the disc spinning around the sun, they say.

The astrophysicists think the blast occurred within 300 light years from the sun and flooded the disc with enough energy to fuse material weighing as much as 100 times our Earth into droplets that cooled into chondrules.

The iron-rich chondrules then soaked up gamma rays and X-rays, McBreen said.

McBreen and Hanlon's theory was reported in the latest issue of New Scientist magazine.

The theory implies that solar systems like ours are rare -- chondrules likely settle quickly and may or may not become planets.

"Forming chondrules really is a long-standing problem, so if this mechanism accounts for them, that would be pretty fantastic," said Alan Boss, an astrophysicist at the Carnegie Institution in Washington.

Astronomers have long wondered what caused clumps of dust circling our young sun to melt into rocky beads rich in iron and silicon, or the chondrules that make up the bulk of meteorites.

The burst, thought to be one of the most powerful of its kind in the universe's history, could be the result of a stellar explosion called a supernova.

But Boss reportedly was unsure that such an unlikely event could be responsible for something as crucial as the formation of our solar system.

"I don't think you'd want to invoke it unless it takes care of everything," he said.

McBreen and Hanlon plan to publish their results in an upcoming issue of Astronomy and Astrophysics.