Discovery of the Carina flare with NANTEN; Evidence for a supershell that triggered the formation of stars and massive molecular clouds

We present extensive observations of the Carina arm region in the 2.6 mm CO (J = 1-0) emission with the NANTEN telescope in Chile. The observations ha ve revealed 120 molecular clouds which are distributed in an area of 283 de grees < l < 293 degrees and 2.degrees 5 < b < 10 degrees. Because of its ve rtical elongation to the galactic plane, the clouds are named the Carina fl are. HI and far-infrared emissions show a cavity-like distribution correspo nding to the molecular clouds, and soft; X-ray emission appears to fill thi s cavity. It is shown that the Carina flare represents a supershell at a di stance of a few kpc that has been produced by about 20 supernova explosions , or equivalent stellar winds of OB stars, over the last similar to 2 x 10( 7) yr. The supershell consisting of molecular and atomic neutral gas involv es a total mass and kinetic energy of greater than or similar to 3 x 10(5) M. and greater than or similar to 3 x 10(50) erg, respectively, and the ori ginally injected energy required is about 100-times this current kinetic en ergy in the shell. It is unique among supershells known previously because of the following aspects: i) it exhibits evidence for the triggered format ion of intermediate-to-high-mass st ars and massive molecular clouds of 10( 2)-10(4) M., and ii) the massive molecular clouds formed are located unusua lly far above the galactic plane at z similar to 100-500 pc.