Ionized Gas Kinematics and Morphology in Sgr B2 Main on 1000 AU Scales

Abstract

We have imaged the Sgr B2 Main region with the Very Large Array in the BnA configuration (${\theta }_{beam}$ = 0\farcs13) in both the H52$\alpha$ (45.453 GHz) radio recombination line (RRL) and 7 mm continuum emission. At a distance of 8500 pc, this spatial resolution corresponds to a physical scale of 0.005 pc ($\sim$1100 AU). The current observations detect H52$\alpha$ emission in 12 individual ultracompact (UC) and hypercompact (HC) HII regions. Two of the sources with detected H52 $\alpha$ emission have broad ($\Delta$V${}_{FWHM}\sim$50 \kms) recombination lines, and two of the sources show lines with peaks at more than one velocity. We use line parameters from the H52$\alpha$ lines and our previous H66$\alpha$ line observations to determine the relative contribution of thermal, pressure and kinematic broadening, and electron density. These new observations suggest that pressure broadening can account for the broad lines in some of the sources, but that gas motions (e.g. turbulence, accretion or outflow) contribute significantly to the broad lines in at least one of the sources (Sgr B2 F3).

10 pages, 2 figures

References in corpus (2)

• The Early Evolution of Massive Stars: Radio Recombination Line Spectra
• Submillimeter continuum observations of Sagittarius B2 at subarcsecond spatial resolution

Cited by in corpus (5)

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• Evidence of Short Timescale Flux Density Variations of UC HII regions in Sgr B2 Main and North
• Structure and kinematics of shocked gas in Sgr B2: further evidence of a cloud-cloud collision from SiO emission maps
• Ionized Gas Motions and the Structure of Feedback Near a Forming Globular Cluster in NGC 5253
• Ultracompact HII regions with extended emission: The case of G43.89-0.78 and its molecular environment