Radio continuum and radio recombination line observations of Sagittarius B2

VLA radio continuum and H110α radio recombination line observations of Srg B2 (G0.7-0.0) are presented with spatial resolutions ranging from 3″ to 20″. The goals of the continuum study were (1) imaging the extended component of Sgr B2. The flux density of this component accounts for ∼50% of the total flux density of the region at 20 cm. (2) examination of the less well studied compact sources of this region. Several shell-like and cometary H II regions were discovered. Physical parameters, such as emission measures and electron densities, were derived. The goals of the recombination line study were (1) investigation of the kinematics of the ionized gas. Results show that the kinematics of the gas in Sgr B2 are complex. Although most of the ionized gas has velocities in the range 50-70 km s^-2, there is also some gas at velocities of ∼100 km s^-1. In addition, there are three sources with shell-like morphologies that have large line widths, suggesting mass motions of the ionized gas (e.g., expansion). (2) Examination of electron temperatures. The electron temperatures of sources in Sgr B2 range from 4700 K to ∼10,000 K. The average value of 7150 K is similar to that found in Galactic disk regions. However, this value is significantly higher than the average value of 5050 K found in Sgr B1, which is a massive star-forming region located 10′ (20 pc) south of Sgr B2. Metallicity differences are probably the major cause of the temperature difference between these two regions.