The Mt John University Observatory Search For Earth-mass Planets In The Habitable Zone Of Alpha Centauri

摘要

The "holy grail" in planet hunting is the detection of an Earth-analog: aplanet with similar mass as the Earth and an orbit inside the habitable zone.If we can find such an Earth-analog around one of the stars in the immediatesolar neighborhood, we could potentially even study it in such great detail toaddress the question of its potential habitability. Several groups have focusedtheir planet detection efforts on the nearest stars. Our team is currentlyperforming an intensive observing campaign on the alpha Centauri system usingthe Hercules spectrograph at the 1-m McLellan telescope at Mt John UniversityObservatory (MJUO) in New Zealand. The goal of our project is to obtain such alarge number of radial velocity measurements with sufficiently high temporalsampling to become sensitive to signals of Earth-mass planets in the habitablezones of the two stars in this binary system. Over the past years, we havecollected more than 45,000 spectra for both stars combined. These data arecurrently processed by an advanced version of our radial velocity reductionpipeline, which eliminates the effect of spectral cross-contamination. Here wepresent simulations of the expected detection sensitivity to low-mass planetsin the habitable zone by the Hercules program for various noise levels. We alsodiscuss our expected sensitivity to the purported Earth-mass planet in an3.24-d orbit announced by Dumusque et al.~(2012).