Saturday, June 2, 2007

Stellar privacy at risk?

So what if Google is zooming its lenses into every peep hole in America? Astronomers have come up with a good close-up, too: they've captured the first image of a relatively normal, hydrogen-burning star (other than our sun). And they discovered that it is fat.

So, taking pictures of stars seems like the kind of thing astronomers would have gotten around to by now. But it turns out that imaging the surface of a star is hard. Until now, only bloated-up red giants were big enough to appear as anything more than single points of light in astronomers' images.

The imaged star, Altair, is pretty close to Earth--it's only about 15 light years away--and it's a "rapid rotator," which gives it what one of those weight-loss drug ads might call "belly bulge." That is, it's a distorted sphere, wider around the equator than around the poles.

The team had to jump through some technical hoops to snap the shot: they used four infrared telescopes as an interferometer, getting better resolution than they could with a single telescope.

They hope to use the same technique to image other stars and even extrasolar planets.

Read the NSF press release here, or check out more technical information, including a PDF of the Science paper, at author John Monnier's site.

Or learn more about the Center for High Angular Resolution Astronomy (CHARA), the telescope array that Monnier's team used.


Elin said...

I thought that all spheres were fatter at the equator than at the poles. Isn't the Arctic Circle smaller than the Equator?

Wouldn't the earth be a cylinder if it were the same at the ples as at the equator?

Kate said...

Oops, I could have explained this more clearly: a perfect sphere will be wider across the "equator" than at any other line of latitude. But the distance around the equator will be equal to the circumference of any great circle or meridian. The shape of a rapidly rotating star will depart from that of a true sphere.