Simulations of astrometric planet detection in Alpha Centauri by intensity interferometry

Abstract

ABSTRACT Recent dynamical studies indicate that the possibility of an Earth-like planet around α Cen A or B should be taken seriously. Such a planet, if it exists, would perturb the orbital astrometry by $\lt {10}\, {\mu {\rm as}}$, which is 10−6 of the separation between the two stars. We assess the feasibility of detecting such perturbations using ground-based intensity interferometry. We simulate a dedicated set-up consisting of four 40-cm telescopes equipped with photon counters and correlators with a time resolution of $0.1\, \rm ns$, and a sort of matched filter implemented through an aperture mask. The astrometric error from one night of observing α Cen AB is $\approx 0.5\, \rm mas$. The error decreases if longer observing times and multiple spectral channels are used, as (channels × nights)−1/2.