A High-Resolution H i Survey of the Rosette Nebula

We analyzed the gross physical properties of the atomic gas associated with the Rosette Molecular Complex (RMC) which was derived from a new high-resolution 21 cm survey. At the distance of the RMC, the 4 arcmin angular resolution of the survey corresponds to a linear size of 2 pc. The H I maps presented here cover an area of 110 x 60 pc. If the 21 cm emission is optically thin, then the survey mapped an H I mass of 1.5 +/- 0.1 x 10 exp 5 solar masses. The optical nebula is surrounded by three dense H I regions, which roughly trace out the boundary of an H I shell. The shell is located at the periphery of the atomic cloud and is expanding into the cloud at 4.5 km/s. The expansion center is located at (l, b, v) = (206.266 deg, -2.083 deg, 16.0 km/s). A constant expansion velocity implies a dynamical age for the shell of about 4 million years, which is consistent with the age of the central cluster NGC 2244. The total kinetic energy of the expansion is estimated to be 3.8 x 10 exp 48 ergs. This represents about 2 percent of the total (radiative + mechanical) energy available from the central cluster. Thus the central cluster can provide sufficient energy to power the flow through a combination of stellar winds and radiation.