Alpha Centauri Scoped for Earth-Like Planets

March 17, 2008 -- Astronomers have come up with an ambitious, brute-force observational technique to detect Earth-sized and perhaps habitable planets orbiting one of our nearest neighbor stars.

No stranger to science fiction fans, the triple-star system called Alpha Centauri is a tad more than four light-years away. The reality is that one or more Earth-like planets are thought likely to exist around one of the system's two small, almost sun-like stars: Alpha Centauri B.

"You can have planets orbiting each star if [the stars in the multiple star system] are far apart," explains astronomer Javiera Guedes of the University of California at Santa Cruz. Guedes is the lead author on a paper to appear in Astrophysical Journal about not only how to find those planets, but why they are thought to exist there.

Guedes and her colleagues ran and re-ran computer simulations to recreate the Alpha Centauri system over its early planet-birthing period of 200 million years.

No matter the initial conditions, the simulations all led to the formation of different planetary systems. All of them contained at least one Earth-sized planet, some of which formed inside the habitable, liquid-water zone around Alpha Centauri B.

The next challenge for the researchers is how to detect any such planets. The traditional approach is to look for a subtle wobble to the star, which indicates that it has planets swinging around it. The problem is that small, rocky planets are not heavy enough to produce large, easily detectable wobbles.