Can we find Earth-mass planets orbiting our nearest star, alpha Centauri?

I will describe a new program at Mt John that aims to find Earth-mass planets orbiting either alpha Cen A or B, which are solar type stars in a well known binary. We are measuring precise radial velocities using the Hercules spectrograph, which I will describe. At least 10,000 spectra at S/N ~ 500:1 giving 1 m/s precision will be needed. Theoretical studies show that Earth mass planets can have stable orbits to 3 AU and that such planets will form from a proto-planetary disk, for a wide range of initial conditions. I will also discuss the close binary nu Octantis where we have apparently found a Jupiter-mass planet in a stable resonant orbit with just two-fifths of the period of the binary star.
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