SUPERBUBBLE BLOWOUT IN THE GIANT H-II REGION NGC-2363

The velocity field of the giant H II complex NGC 2363 in te SBm galaxy NGC 2366 has been mapped in the ]O-III[ gamma 5007 angstrom line using a scanning Fabry-Perot interferometer. The ]O-III[ line profiles correspond to symmetrical and single component profiles in most of the nebulae of NGC 2366, except in the bright core of the giant H II NGC 2363 where strong splitting of the ]O-III[ line occurs. This splitting is consistent with a bubble 200 pc in diameter expanding with a velocity of 45 km s-1. The total kinetic energy of the bubble is 2 x 10(52) ergs; the kinematic age of the bubble is less than or equal to 2 x 10(6) yr. The bubble could be produced by the sole action of combined stellar winds from the central clusters of O-B stars. A well-defined sector, 150 pc wide, of the H II complex originating at the bubble shows systematic receding velocities; it is suggested that this region acts as a vent through which gas escapes into the halo of the galaxy. Large H-alpha shells are observed in the surroundings of NGC 2363. There is also evidence for a very broad and low-intensity [OMICRON-III] high-velocity (approximately 1000 km s-1) component associated with the bubble.