Stars Are Born in Pairs

A fascinating new theory.
The new assertion is based on a radio survey of a giant molecular cloud filled with recently formed stars in the constellation Perseus, and a mathematical model that can explain the Perseus observations only if all sunlike stars are born with a companion.

"We are saying, yes, there probably was a Nemesis, a long time ago," said co-author Steven Stahler, a UC Berkeley research astronomer.

"We ran a series of statistical models to see if we could account for the relative populations of young single stars and binaries of all separations in the Perseus molecular cloud, and the only model that could reproduce the data was one in which all stars form initially as wide binaries. These systems then either shrink or break apart within a million years."...

Using these data, Sadavoy and Stahler discovered that all of the widely separated binary systems - those with stars separated by more than 500 AU - were very young systems, containing two Class 0 stars. These systems also tended to be aligned with the long axis of the egg-shaped dense core. The slightly older Class I binary stars were closer together, many separated by about 200 AU, and showed no tendency to align along the egg's axis.


douglas said...

That last bit of info about them lining up with the long axis of the "egg shaped dense core" suggested to me that perhaps the foci of the egg are the points of condensation that form stars, and it's the shape of this 'star factory' that produces pairs, not that ALL stars are produced in pairs.. Reading the link, that's apparently the case, but I'm wondering how they know most star factories are egg shaped? Most nebulae are rather irregular visually- perhaps in other parts of the spectrum they reveal egg shaped cores?

james said...

I assume the actual star-forming cores are embedded in the big clouds. Little bitty knots of stuff--compared to the big cloud. But this finding, if it pans out, suggests to me that the star forming cloud is bigger than we thought, and probably has a pretty large angular momentum to it.