Observation of Extended Red Emission (ERE) in the halo of M82

Low-dispersion spectra have been obtained from 4000 to 9600 \AA~along the axis and across the dusty halo of the galaxy M82. The spectra of the halo are explained in terms of scattering of the galactic light by dust grains: when divided by the spectrum of the galaxy, they reveal a broad emission band, similar to, although wider than the bump of Extended Red Emission (ERE) commonly observed in galactic reflection nebulae. The feature is particularly well marked in the filamentary parts of the halo. This is the first detection of ERE outside of our Galaxy.