Alpha Centauri may harbor Earth-like planets

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Washington, March 8: A new study led by astronomers at the University of California, Santa Cruz (UCSC), has suggested that the star system Alpha Centauri might harbor Earth-like planets, which could be detected using existing techniques.

As part of the study, UCSC graduate student Javiera Guedes used computer simulations of planet formation to show that terrestrial planets are likely to have formed around the star Alpha Centauri B and to be orbiting in the "habitable zone" where liquid water can exist on the planet's surface. To study planet formation around Alpha Centauri B, the team ran repeated computer simulations, evolving the system for the equivalent of 200 million years each time.

Because of variations in the initial conditions, each simulation led to the formation of a different planetary system. In every case, however, a system of multiple planets evolved with at least one planet about the size of Earth. In many cases, the simulated planets had orbits lying within the habitable zone of the star.

The researchers then showed that such planets could be observed using a dedicated telescope. "If they exist, we can observe them," said Guedes, who is the first author of a paper describing the new findings.

The Doppler detection method, which has revealed the majority of the 228 known extrasolar planets, measures shifts in the light from a star to detect the tiny wobble induced by the gravitational tug of an orbiting planet.

"Factors that favor the use of this technique for Alpha Centauri B include the brightness of the star and its position in the sky, which gives it a long period of observability each year from the Southern Hemisphere," said Gregory Laughlin, professor of astronomy and astrophysics at UCSC.

Debra Fischer of San Francisco State University is leading an observational program to intensively monitor Alpha Centauri A and B using the 1.5-meter telescope at the Cerro Tololo Inter-American Observatory in Chile.

The researchers hope to detect real planets similar to the ones that emerged in the computer simulations. "I think the planets are there, and it's worth a try to have a look," said Laughlin.


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