http://web.mit.edu/n...dstar-091709.html

A pair of unusual stars known as DI Herculis has confounded astronomers for three decades, but new observations by MIT researchers and their colleagues have provided data that they say solve the mystery once and for all.

It has long been clear that there was something odd going on in this double-star system, but it wasn't clear just what that was. The precession of the orbits of the two stars around each other — that is, the way the plane of those orbits change their tilt over time, like the wobbling of a top as it winds down — seems to take place four times more slowly than established theory says it should. The anomaly is so unexpected that at one point it was seen as possible evidence against Einstein's long-accepted theory of relativity.

The solution turns out to be simple, but it also leads you to wonder just how the stars ended up that way.

What I find more interesting is that the recent spat of discoveries about other stars and solar systems are messing up our neat models of how they form. Scientists are finding a lot more exceptions and oddities then expected. It could be a quirk of the observation process (we can see the odd ones more easily) but more likely it indicates that we don't understand the process very well. Either our model is wrong or there is some other factor throwing it off.

Jay