Alpha Centauri Has a Planet

Artist's impression of the planet around Alpha Centauri B

European astronomers have discovered a planet with about the mass of the Earth orbiting a star in the Alpha Centauri system — the nearest to Earth. It is also the lightest exoplanet ever discovered around a star like the Sun. The planet was detected using the HARPS instrument on the 3.6-metre telescope at ESO’s La Silla Observatory in Chile. The results will appear online in the journal Nature on 17 October 2012.

This is incredibly exciting to me! A few years ago, when I worked on Hubble, I looked into using it to search for planets around Alpha Cen. I worked out some simulations to see if we could detect anything, and at best we could see a Jupiter-sized planet orbiting far enough out that its faint light wouldn’t be blasted out by the star itself. It was deemed too risky an observation (too low a chance of payoff) so we didn’t get time on the telescope to make it. We’d never have seen this planet anyway; looking for a planet reflecting its star’s light is very different than looking for the Doppler shift. Obviously!

Also, c’mon. This is Alpha Centauri! Famed and fabled in a thousand science fiction stories. It’s where the Robinson family was supposed to go in “Lost in Space”. It’s where Zefram Cochrane lived in “Star Trek”. It’s where the Fithp came from in Footfall. Because the system is bright and close, and the stars so close to being like our own Sun, they’re an obvious place to put aliens. Plus, you get the exotic locale of a binary star plus the red dwarf thrown in on top. It’s perfect!

So I, and a lot of people like me, grew up hoping against hope we’d find a planet around one of these stars someday.

And here we are.

— Phil Plait (Bad Astronomer)

via ESO and Bad Astronomer