The Molecular Component of the Galactic Center Arched Filaments H [CSC]ii[/CSC] Complex: OVRO Observations of the CS [ITAL]J[/ITAL] = 2–1 Line

The Owens Valley Radio Observatory (OVRO) millimeter array was used to makeobservations of the CS(2-1) line (at 97.981 GHz) arising from the G0.07+0.04region of the ``-30 km/s'' molecular cloud near the Galactic center with aspatial resolution of ~8". The ionized edges of this cloud forms the ArchedFilament HII regions which are ionized by the adjacent Arches stellar cluster.The OVRO data were combined with single-dish data obtained at the 30-m IRAMtelescope by Serabyn & Guesten (1987). A comparison of this CS(2-1) data andthe H92alpha recombination line data of Lang, Goss & Morris (2001) reveals thatthe ionized and molecular gas are physically related, but that their velocitiesin this region differ by up to 35 km/s. This difference in velocity can beunderstood if the gas that gave rise to the G0.07+0.04 HII region has beenfully ionized. An overall comparison of the molecular and ionized gas acrossthe entire -30 km/s cloud based on the single dish CS(2-1) data and theH92alpha line data illustrates that such differences in velocity between theionized and molecular gas are common and that the geometrical arrangement ofthese components is complicated. Much of the ionized gas resides on the nearside (to the observer) of the molecular cloud; however, in several regions,some molecular material must lie in front of the HII region. The Arches stellarcluster therefore appears to be located in the midst of the molecular cloudssuch that some of the near-side cloud surfaces along our line of sight have notbeen exposed to the ionizing radiation.Comment: accepted for publication in AJ, November 2002 issue; 28 pages with 13 figures -quality reduced in many cases - in preprint style (some figure captions shortened