Sauvage, M Blommaert, Joris Boulanger, F Cesarsky, CJ Cesarsky, DA Desert, FX Elbaz, D Gallais, P Joncas, G Metcalfe, L Okumura, K Ott, S Siebenmorgen, R Starck, JL Tran, D Vigroux, L
Astronomy and astrophysics vol:315 issue:2 pages:L89-L92
We have obtained the first images of the 6.75 and 151 mu m continuum emission in the Whirlpool galaxy with ISOCAM, the infrared camera of the ISO1. These data reveal the well-developed, spiral arms of the galaxy, in addition to diffuse emission between arms and in the outer regions of the disk. There is a striking correspondence with the 15 mu m emission and the Her emission over the galaxy. We tighten this link by looking at the properties of the individual HII regions and show that the 15 mu m emission traces massive star formation and is not affected by extinction as is H alpha. The data show systematic mid-infrared color variations perpendicular to the arms, which we interpret as two distinct dust components contributing to the mid-infrared emission. We examine the implication of these color variations in light of our current understanding of dust at these wavelength.