INFRARED SPECTRAL OBSERVATIONS OF THE BNKL COMPLEX IN ORION

Infrared spectroscopic observations have been made with sufficient spatial resolution to separate some of the members of the BNKL infrared complex in the Orion Nebula. 8-13 μm spectra of BN, IRc2 and IRc4 together with 3-4 μm spectra of BN and IRc2 are presented. These spectra show significantly more extinction attributed to water ice to IRc2 than to BN, and the extinction attributed to silicate grains also increases in the sequence BN, IRc2 and IRc4. The silicate absorption feature observed in the case of IRc4 has a significantly different shape from that observed in most heavily obscured infrared sources, but this is shown to be a natural consequence of a large amount of absorbing material being close to the source of luminosity. These observations are interpreted in terms of independent sources of comparable luminosity situated progressively deeper within the Orion molecular cloud. © 1981 Royal Astronomical Society.