The Molecular Counterpart of the Galactic Center Arched Filament HII Complex: OVRO Observations of the CS(2-1) Line

Abstract

The Owens Valley Radio Observatory (OVRO) millimeter array was used to make observations of the CS(2-1) line (at 97.981 GHz) arising from the G0.07+0.04 region of the ``-30 km/s'' molecular cloud near the Galactic center with a spatial resolution of ~8". The ionized edges of this cloud forms the Arched Filament 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 IRAM telescope by Serabyn & Guesten (1987). A comparison of this CS(2-1) data and the H92alpha recombination line data of Lang, Goss & Morris (2001) reveals that the ionized and molecular gas are physically related, but that their velocities in this region differ by up to 35 km/s. This difference in velocity can be understood if the gas that gave rise to the G0.07+0.04 HII region has been fully ionized. An overall comparison of the molecular and ionized gas across the entire -30 km/s cloud based on the single dish CS(2-1) data and the H92alpha line data illustrates that such differences in velocity between the ionized and molecular gas are common and that the geometrical arrangement of these components is complicated. Much of the ionized gas resides on the near side (to the observer) of the molecular cloud; however, in several regions, some molecular material must lie in front of the HII region. The Arches stellar cluster therefore appears to be located in the midst of the molecular clouds such that some of the near-side cloud surfaces along our line of sight have not been exposed to the ionizing radiation.

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)

References in corpus (1)

• A VLA H92alpha Study of the Arched Filament Complex Near the Galactic Center

Cited by in corpus (22)

• Hot and Diffuse Clouds near the Galactic Center Probed by Metastable H3+
• A $\lambda$20cm Survey of the Galactic Center Region I: Detection of Numerous Linear Filaments
• Interacting Cosmic Rays with Molecular Clouds: A Bremsstrahlung Origin of Diffuse High Energy Emission from the Inner 2deg by 1deg of the Galactic Center
• The Origin of Diffuse X-ray and $\gamma$-ray Emission from the Galactic Center Region: Cosmic Ray Particles
• The XMM-Newton view of the central degrees of the Milky Way
• The Interplay between Star Formation and the Nuclear Environment of our Galaxy: Deep X-ray Observations of the Galactic Center Arches and Quintuplet Clusters
• The Central 300 pc of the Galaxy probed by infrared spectra of H${}_3^{+}$ and CO: part I. Predominance of warm and diffuse gas and high H${}_2$ ionization rate
• Nonthermal X-rays from low-energy cosmic rays: Application to the 6.4 keV line emission from the Arches cluster region
• Detection of Widespread Hot Ammonia in the Galactic Center
• Spitzer IRS Observations of the Galactic Center: Shocked Gas in the Radio Arc Bubble
• GBT Multiwavelength Survey of the Galactic Center Region
• Stellar Winds and Embedded Star Formation in the Galactic Center Quintuplet and Arches Clusters: Multifrequency Radio Observations
• X-ray Observations of Stellar Clusters Near the Galactic Center
• A High-Resolution Survey of HI Absorption toward the Central 200 pc of the Galactic Center
• The Atacama Cosmology Telescope: Microwave Intensity and Polarization Maps of the Galactic Center
• Kinematics and properties of the Central Molecular Zone as probed with [C II]
• SOFIA/FORCAST Galactic Center Legacy Survey: Overview
• SOFIA FIFI-LS Observations of Sgr B1: Ionization Structure and Sources of Excitation
• An Infrared Study of the Dust Properties and Geometry of the Arched Filaments HII Region with SOFIA/FORCAST
• Multiwavelength Observations of Massive Stellar Cluster Candidates in the Galaxy
• Warm ISM in the Sgr A Complex. I: Mid-J CO, atomic carbon, ionized atomic carbon,and ionized nitrogen sub-mm/FIR line observations with the Herschel-HIFI and NANTEN2/SMART telescopes
• Unveiling the Massive Stars in the Galactic Center