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Doppler detection method

Alpha Centauri Should Contain Earth-like Planets

It’s been the destination of interstellar travelers in science fiction writing for so long now that one would almost be forgiven for thinking we’d already colonized. But Alpha Centauri, the three-star system closest to our own Sun, is now the center of real science. 

UCSC graduate student Javiera Guedes, the lead author of a paper soon to be published in the Astrophysical Journal, has shown that terrestrial planets are likely to have formed around Alpha Centauri B, and that these planets should be orbiting in the “habitable zone.”

“If they exist, we can observe them,” said Guedes who, along with his co-authors, also showed that such planets would be observable if a telescope was dedicated to their search.

Guedes used a series of planet formation computer simulations to determine that terrestrial planets have probably formed around the star. The team ran repeated computer simulations, which ran on a time frame of 200 million years each time. They varied the beginning conditions each time, and thus created a different result each time. However, each time a system of multiple planets evolved with at least one planet – approximately the size of Earth – forming. In many of these simulations, this planet was often found to be orbiting within the habitable zone of the star.

So next on the table for the team is to find one of these planets; but that is not an easy task.

The majority of the 228 known extrasolar planets discovered have been located using the Doppler detection method; a system by which one measures the shifts in the light from a star to detect a tony wobble induced by the gravitational tug of an orbiting planet. However because the team is looking for an Earth sized planet, the gravitational tug is not huge.

Its brightness and its position in the sky are both positive factors that make the Alpha Centauri search plausible; the latter giving the team a long period of observability each year from the Southern Hemisphere.

Co-author Debra Fischer, of San Francisco State University, will be leading the observational program from the 1.5-meter telescope at the Cerro Tololo Inter-American Observatory in Chile. The researchers are hoping that the planets that emerged in the simulations will also appear in reality.