High-resolution imaging of ultracompact HII regions II. G5.89-0.39 revisited

We present the results of an extensive imaging campaign on the ultracompact HII region G5.89-0.39 at near- and mid-infrared wavelengths. High-resolution data were taken in the H, K-1, and L bands using ESO's adaptive optics system ADONIS. They are complemented by conventional narrowband images in Pry and H-2(1 - 0)S1 as well as by mid-infrared broad- and narrow-band images. We also mapped the 1.3 mm continuum emission from the source using the SEST. We use our data to consistently explain the morphological appearance of G5.89-0.39 at all observed wavelengths as well as its spectral energy distribution. The complete model of the source consists of a spherical shell of dust with an inner, dust-free cavity of 7.6 x 10(16) cm radius surrounding a star of spectral type O6 ZAMS. Two outflows escape this shell in opposite directions. Half of the whole configuration is evidently obscured by a very massive cloud of cold dust. Comparisons with earlier models and other ultracompact HII regions are drawn to put G5.89-0.39 in the context of massive star formation.