ISOCAM observations of the Antennae Galaxies.
Altieri, B.; Cesarsky, C.; Boulanger, F.; Okumura, K.; Fransson, C.; Madden, S.; Vigroux, L.; Gallais, P.; Cesarsky, D.; Claret, A.; Tran, D.; Mirabel, F.; Levine, D.
Abstract
We have mapped the Antennae Galaxies (NGC4038/39) in the 6.7 and 15μm continuum emission using ISOCAM (Cesarsky et al., 1996A&A...315L..32C) with =~5 - 8" resolution. Spectrophotometric observations with the CVF in the spectral range 5.5 to 16.5μm have also been obtained. We compare the distribution of the infrared emission in the 2 nuclei and in the overlap region where the disks of the galaxies collide. The emission longward of 12.5μm is dominated by ionized gas and by reprocessing of UV flux by dust. The overlap region is the most active star forming area in the system and contributes to more than half of the total infrared luminosity between 12.5 and 18μm. The brightest knot in the overlap region has a surface brightness at 15μm which is 5 times larger than the nuclei of the parent galaxies. From the [NeIII] and [NeII] lines, we estimate a lower limit to the effective temperature of the ionizing stars of 39,500K and 37,000K in the overlap region and the nuclei, respectively.