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Precision Millimeter Astrometry of the α Centauri AB System

July 2021 • 2021AJ....162...14A

Authors • Akeson, Rachel • Beichman, Charles • Kervella, Pierre • Fomalont, Edward • Benedict, G. Fritz

Abstract • Alpha Centauri A is the closest solar-type star to the Sun and offers the best opportunity to find and ultimately to characterize an Earth-sized planet located in its habitable zone. Here, we describe initial results from an Atacama Large Millimeter/submillimeter Array (ALMA) program to search for planets in the α Cen AB system using differential astrometry at millimeter wavelengths. Our initial results include new absolute astrometric measurements of the proper motion, orbital motion and parallax of the α Cen system. These lead to an improved knowledge of the physical properties of both α Cen A and B. Our estimates of ALMA's relative astrometric precision suggest that we will ultimately be sensitive to planets of a few tens of Earth mass in orbits from 1 to 3 au, where stable orbits are thought to exist.

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Rachel Akeson

IPAC Deputy Director