The Chamaeleon infrared nebula revisited. Infrared imaging and spectroscopy of a young stellar object

Abstract

We are presenting spectroscopic and imaging data on the Chamaeleon Infrared Nebula (Cha IRN). Imaging was done between 1 and 2.5mu m and at 10mu m. Spectra of the object were obtained in the 2.1mu m - 4.6mu m range by ground-based measurements as well as using ISOPHOT-S in the 2.5mu m - 11.6mu m range. By combining these data with a K-band speckle image and IRAS-LRS data, we draw a complete picture of the source. The system's geometry, consisting of central source, disk, and bipolar outflow cavities, is determined directly from the observational data. Thereby we confirm earlier assumptions on the basic geometry of the system as well as support newer speculations by Gledhill et al. (1996) about the presence of a binary system inside the Cha IRN. Additionally, we fit a radiative transfer model to the spectral energy distribution and derive the dust composition from the ISOPHOT spectra and give the resulting abundance ratios. The spectroscopic data point to an unusually silicate-poor environment of this young stellar object or a special geometric arrangement which leads to a suppression of the feature. They also indicate one of the most prominent H_2O ice features known as well as the presence of CO, CO_2, and possibly NH_3 ice. Based on observations collected at the European Southern Observatory, La Silla, Chile