Friday, February 10, 2012

Blue Stragglers

Some old globular clusters have a few hot blue stars in the mix, which isn't quite what you'd expect. Most easily condensable gas should have been "boiled" off long ago, so either the cluster scooped them up when moving through another part of the galactic cluster, or they were somehow created out of violent interactions between the (extremely crowded) stars in the core of the cluster.

Apparently some of those hot blue stars have a surprisingly fast rotation rate: 75 times faster than the sun. That strongly suggests some kind of collision or very near miss, which would certainly stir things up in a star. What that would do to the internal workings of the star would be the subject of a research project and not a blog post, but anybody can see it would shine quite a bit hotter, if only because internal convection is faster for a while.

But that rotation speed--3 revolutions per day--would have other interesting effects. If the star is about the same size as the Sun the equator would be moving at 305km/hour. Coriolis effects would make for some large storms, and the storms would pull deeper and hotter gas up. I don't know if these would be visible at the surface, but the side effects ought to be. The polar regions should be less effected, and so have less of the hotter gas welling up, and so be cooler. That suggests a kind of bulk flow of hot gas from the equatorial regions to the pole, which would tend to disrupt the natural banding (like Jupiter's) you ought to get.

If you could see it in the appropriate wavelengths, it should be a lively show, and you could almost watch it spinning.

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