The interplay between molecular and ionised gas surrounding the massive embedded star AFGL 4176

Abstract

In order to investigate whether the feedback produced by photo-ionisation has an important effect on the geometry of the circumstellar dust and gas around forming massive stars, we have observed the luminous southern embedded star AFGL 4176 in transitions of NH3 and the hydrogen recombination line H68α. We present our preliminary results, which show a compact HII region embedded in a parsec-scale (radius ~0.7 pc) rotating envelope/torus. In addition, the HII region is found to be offset from the centre of the envelope, and the velocity gradient in the ionised gas is not aligned with the rotation axis of the envelope, suggesting complex dynamics and multiplicity.