Stars Are Born Like Popcorn, Mystery Deepens Over Sun’s Origin

By | January 20, 2012

New 3-D computer simulations have delivered a crushing blow to the strongest contender for our sun’s birthplace, astronomers say, returning the quest for the solar system’s origins to square one.

Stars like the sun typically form in clusters with other stars. Many clusters are spread out so that the stars drift apart, but others are denser, and gravity keeps their stars close together.

The sun now stands alone, so astronomers think our star—and its newborn solar system—was either ejected from its birth cluster or drifted away from its siblings about 4.5 billion years ago.

Messier 67, or M67, is a hundred-light-year-wide ball of stars that recently passed some crucial “paternity tests” for being the sun’s birthplace.

The cluster not only harbors stellar bodies similar in temperature, age, and chemistry to our sun, but M67 also drifts a relatively close 2,900 light-years away.

A new study of M67, however, undermines the existing lines of evidence and leaves almost no chance that our star could hail from the region.

Computer simulations show that a rare chain of events—two or three massive stars lining up just right to make a gravitational slingshot—would have been needed to kick the sun out of M67 and get it where it is today.

Such a powerful event is a probabilistic Hail Mary and, even if it had occurred, the speed of the kick would have ripped our nascent solar system to shreds.

“When you have that kind of gravitational disruption, planetary disks evaporate, and existing planets acquire energy and can be expelled,” said study leader Barbara Pichardo, an astrophysicist at the National Autonomous University of Mexico.

Practically all of our galaxy’s 200 to 400 billion stars, including the sun, were born through the gravitational collapse of diffuse clouds of dust and gas sprinkled across the Milky Way by previous generations of long-dead stars.

These star-forming clouds mix a little bit, but stars of similar chemistry tend to appear within the same clouds around the same time.

“It’s like popcorn,” Pichardo said. “They heat up for a long time and then pop-pop-pop, they are born.” …

via Mystery Deepens Over Where Sun Was Born.

For fun, and much safer than looking at the sun:

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