CHARA array angular diameters of HR 8799

Using the CHARA Array interferometer, we measure HR 8799's limb-darkened angular diameter to be 0.342+/-0.008mas (an error of only 2%). By combining our measurement with the star's parallax and photometry from the literature, we greatly improve upon previous estimates of its fundamental parameters, including stellar radius (1.44+/-0.06R_{sun}_), effective temperature (7193+/-87K, consistent with F0), luminosity (5.05+/-0.29L_{sun}_), and the extent of the habitable zone (HZ; 1.62-3.32AU).

These improved stellar properties permit much more precise comparisons with stellar evolutionary models, from which a mass and age can be determined, once the metallicity of the star is known. Considering the observational properties of other {lambda} Bootis stars and the indirect evidence for youth of HR 8799, we argue that the internal abundance, and what we refer to as the effective abundance, is most likely near solar.