Mass and radius measurements of stars are important inputs for models of stellar structure. Binary stars are of particular interest in this regard, because astrometry and spectroscopy of a binary together provide the masses of both stars as well as the distance to the system, while interferometry can both improve the astrometry and measure the radii of the stars. In this work, we simulate parameter recovery from intensity interferometry, especially the challenge of disentangling the radii of two stars from their combined interferometric signal. Two approaches are considered: separation of the visibility contributions of each star with the help of differing brightness ratios at different wavelengths, and direct fitting of the intensity correlation to a multiparameter model. Full image reconstructions is not attempted. Measurement of angular radii, angular separation, and first-order limb-darkening appears readily achievable for bright binary stars with current instrumentation.
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 <10μas, 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 setup consisting of four 40-cm telescopes equipped with photon counters and correlators with time resolution $0.1\, \rm ns$, 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.
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