OBSERVATIONS OF CO LINES IN SOUTHERN SPIRAL GALAXIES

Six southern spiral galaxies, with diameters between 5' and 8', were m apped with the SEST in the (CO)-C-12(1-0) line. CO emission was detect ed in five of the galaxies. The 43'' beam of the SEST, at 115 GHz, was small enough for determining the general distribution of the gas, whi ch is centrally peaked in all the cases, and the velocity field from w hich we could derive the major axis position angle and the rotation cu rve. The latter is, in general, very steep at the centre and quite fla t after the turn-over point. It was used to estimate the total mass of the galaxy up to the farthest measured point. The gas mass was estima ted from the CO and H I global velocity profiles. On three of the gala xies the (CO)-C-12(2-1) and (CO)-C-13(1-0) lines were also observed on their centres, the first one on a 10'' grid, covering a region of 20' ' x 20'', and the second on one point towards the centre. The average ratio between the intensities of the (CO)-C-12(2-1) and (CO)-C-12(1-0) spectra is 1.3 in the three cases. The detections of the (CO)-C-13(1- 0) were only marginal. A good correlation has been found between the C O and the continuum emission at 843 MHz.