Observations of the IR recombination line emission from massive young stellar objects

Abstract

We present new, high-resolution observations of the infrared H I emission lines of massive YSOs. The widths of the Br alpha, Brgamma and Pfgamma lines indicate outflowing material with velocities of 100-200 km s^-1 for all the sources observed. We discuss the morphology of the line profiles and examine the velocity-resolved line ratios. Three of the sources appear to be dominated by an expanding optically thick stellar wind, whilst BN shows some evidence for an additional narrow, more optically thin component, as we found previously for S106IR. The object M17 SW IRS1 has line profiles more like those of a Herbig Be star.