2002ApJ...566..982Z

We present observational studies of a high-mass star-forming region AFGL 5142 in the NH₃ (J,K)=(1,1), (2,2), (3,3), and (4,4) inversion transitions. We discover a compact structure of 1" (or 1800 AU) in NH₃ emission toward the position of a high-mass young star. The star, with a spectral type of B2 if it is at the zero-age main sequence, excites a weak centimeter continuum source and drives a well-collimated SiO jet. The compact NH₃ structure, with a temperature of 70 K, gives rise to a broad NH₃ line emission of 6.4 km.s^–1 (FWHM). The small size of the NH₃ feature, broad line emission, and the association with a SiO jet indicate that the object is most likely an unresolved rotating disk. The compact disk is embedded in a flattened core of gas temperatures of about 20 K. The extended core delineates an X shape with the SiO jet located in the void of the dense and cold NH₃ gas. A faint component of NH₃ emission can be identified, especially in the highly excited NH₃ (3,3) and (4,4) lines, tracing the SiO jet. This component, arising from hot gas of about 170 K, is likely heated by shocks in the outflow. The coincidence of a disk and a jet with the radio continuum source toward AFGL 5142 indicates that this high-mass star may have formed via a disk-mediated accretion process.