A COMPREHENSIVE STUDY OF THE PECULIAR SPIRAL GALAXY NGC-1808 .1. RADIO-CONTINUUM AND CO LINE OBSERVATIONS

We have observed the peculiar galaxy NGC 1808 in the CO line and in the radio continuum using the SEST1 and the VLA2. Linear radio polarization is found, with degrees of up to 30% outside the central active region, indicating the presence of a large-scale magnetic field. A comparison of the lambda-lambda-20 cm and 6 cm radio continuum data yields a steep spectral index for the central region, suggesting a predominantly nonthermal origin of the emission. The CO distribution shows a central concentration. The velocity field is disturbed, hinting at peculiar motions of molecular gas within the minor axis regions. Evidence is found for a rotating molecular ring of about 1.4 kpc diameter. The ratio of the CO(2-1)/CO(1-0) lines of greater-than-or-equal-to 1 is characteristic for an optically thin, hot gas, similar to that seen in M82. H-alpha observations reveal the presence of a linear string of H(II) clumps directed away from the central starburst region, most likely not coincident with the disk of the galaxy. Its possible origin as well as the resemblence of the central starburst regions of NGC 1808 and M82 are discussed.