The 3.3 Micrometer Feature: The Large Scale Galactic Emission

Abstract

The AROME balloon borne experiment was built in order to perform measurements of IR emission features in extended sources (Field of view = 0.5°). It has shown that the 3.3 micrometer feature is present in the spectrum of the diffuse galactic light. This means that the feature emitting material (PAHs, HACs, QCCs, etc.) is to be considered as a standard component of interstellar grains models. Our aim here is to emphasize the ubiquity of the 3.3 micrometer feature. Historicaly, the infrared emission features were first observed in nebulae of intense UV excitation just because these are the brightest infrared astronomical objects. Actually, the intensity of the 3.3 µm feature (relative to the total far infrared radiation) increases in the most diffuse and less UV-excited regions of the interstellar medium.