The spectral energy distribution of HH 100 IRS

The spectral energy distribution of HH 100 IRS is modeled as a function of dust parameters such as the grain size, the ice volume fraction, and the fluffiness of the particles. The radiative transfer calculations include a detailed treatment of the spectroscopic signature of the ice bands. The infrared spectrum of HH 100 IRS is successfully reproduced if an upper size limit of the grains well below 1 micron is used. Contributions from scattering to the bands superimposed to the long wavelength wing of the 3.08 microns H_2O absorption are thus excluded. The strength of the H_2O ice absorption increases with increasing fluffiness of the particles. Comet-like grains, with sizes above 1micron, result in a poor fit of the observations. An L-band spectrum towards the Herbig-Haro energy source HH 100 IRS is analyzed using a new signal processing technique based on the a trous} wavelet transform. The analysis indicates the presence of an emission band near 3.51 microns which is tentatively assigned to arise from aliphatic CH_2 vibrations.