2018ApJ...865L..18I

The Becklin-Neugebauer (BN) object in Orion has a large proper motion and radial velocity with respect to the gas and other stars in the region where it is presumed to have formed. Multiple dynamical interaction scenarios have been proposed to explain this motion. In one case BN is thought to have interacted with stars in the Trapezium cluster, while in another it is thought to have interacted with source I while deeply embedded in molecular gas. If there is dense gas that has been retained in close proximity to BN, it may be evidence that the latter scenario is favored. We observed BN at high spectral resolution in three windows near 6 µm using the Echelon-Cross-Echelle Spectrograph on board the Stratospheric Observatory for Infrared Astronomy targeting the ν₂ vibrational band of H₂O. Absorption from only three transitions of H₂O is detected, and through kinematic analysis is associated with cool, dense foreground gas, not BN itself. We find no evidence for H₂O absorption or emission at the systemic velocity of BN.