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Gamma Cephei III

September 4, 2012

Astronomers have discovered hundreds of planets in other star systems. Now they’re trying to use those planets to find out how all planets are born.

One thing they want to know is whether all planetary systems are laid out like our own — whether the planets orbit their parent stars in the same plane, as though they were all rolling around a table top.

A team led by Texas astronomer Fritz Benedict is using Hubble Space Telescope to study the layout of several systems. One of them is Gamma Cephei. It consists of two stars, plus a planet orbiting the larger star.

BENEDICT: All my theoretician friends say, ‘Oh, pooh, Fritz, you shouldn’t even bother because it has to lie on the same tabletop, otherwise this system is unstable — it wouldn’t last for longer than 10,000 years or something.’

Even so, the astronomers observed the system from 2008 to 2010. They were looking for a tiny “wobble” in the position of the larger star, caused by the tug of the planet.

But the wobble is tiny, so isolating it is quite a chore. For one thing, Gamma Cephei is moving across the sky as it orbits the center of the galaxy. For another, it’s quite close — only 45 light-years away — so as Earth orbits the Sun, the star shifts position with respect to the background of distant stars. And for yet another, the star also moves as it and its companion star orbit each other. In fact, measuring that orbit has proved to be a big headache. We’ll explain why tomorrow.


Script by Damond Benningfield, Copyright 2012

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