On the Near-Infrared Size of Vega

Near-infrared (2.2 μm) long baseline interferometric observations of Vega are presented. The stellar disk of the star has been resolved, and the data have been fitted with a limb-darkened stellar disk of diameter ΘLD = 3.28 ± 0.01 mas. The derived effective temperature is Teff = 9553 ± 111 K. However, the residuals resulting from the stellar disk model appear to be significant and display organized structure. Instrumental artifacts, stellar surface structure, stellar atmosphere structure, and extended emission/scattering from the debris disk are discussed as possible sources of the residuals. While the current data set cannot uniquely determine the origin of the residuals, the debris disk is found to be the most likely source. A simple debris disk model, with 3%-6% of Vega's flux emanating from the disk at r ≲ 4 AU, can explain the residuals.