We discuss an unusual complex of molecular clouds situated 300 pc above the Galactic plane in the Perseus spiral arm. The complex is associated with the HII region NGC 281 and the IC 1596 cluster, which lie at a distance of 2.9 kpc. The rarity of clouds so far from the plane argues strongly that the seven clouds which form the complex are associated, and yet their velocities are widely dispersed between -50 km/s and -10 km/s. Their mean velocity, however, is close to the velocity expected from Galactic rotation. Physical properties for each of the clouds was determined from the CfA Galactic CO survey (Dame, Hartmann & Thaddeus 2001). On the basis of this CO survey, as well as existing HI surveys, we propose that the clouds are part of an expanding ring of molecular and atomic gas. The ring radius of 135 pc and expansion velocity of 22 km s-1 implies an age of 6 Myr and a total energy of expansion of 1051 ergs; this is comparable to the energy that is released in a supernova or in the wind of an OB star over its lifetime.
American Astronomical Society Meeting Abstracts
- Pub Date:
- December 2001