THERMAL SiO AND H13CO+ LINE OBSERVATIONS OF THE DENSE MOLECULAR CLOUD G0.11-0.11 IN THE GALACTIC CENTER REGION

T. Handa M. Sakano S. Naito, M. Hiramatsu M. Tsuboi


(1) Institute of Astronomy, University of Tokyo, Osawa 2-21-1, Mitaka, Tokyo 181-0011, Japan
(2) Department of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK
(3) Department of Astronomy, University of Tokyo, Hongo 7-3-1, Bunkyo, Tokyo 113-0033, Japan
(4) Nobeyama Radio Observatory, National Astronomical Observatory Japan, Nobeyama, Minami-Saku, Nagano 384-1305, Japan; Department of Astronomical Science, Graduate University for Advanced Studies (Soken-Dai), Mitaka, Tokyo 181-8588, Japan; and Department of Astronomy, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-0033, Japan

Paper: ApJ, 636, 261

EPrint Server: astro-ph/0510565

Abstract:

We obtained the first view in H13CO+ J=1-0 and a high-resolution map in thermal SiO lines of G0.11-0.11, which is a molecular cloud situated between the Galactic Center radio arc and Sgr A. From a comparison with previous line observations, we found that the H13CO+ J=1-0 line is optically thin, whereas the thermal SiO lines are optically thick. The line intensity in H13CO+ J=1-0 shows that the cloud has a large column density, up to N(H2)=(6-7)*1023 cm-2, which corresponds to about 640-740 mag in A_V or 10-12 mag in A_25 mu m. The estimated column density is the largest known of any even in the Galactic center region. We conclude from the intensity ratio of SiO J=1-0 to CS J=1-0 that emitting gas is highly inhomogeneous for SiO abundance on a scale smaller than the beam width 35''.

Preprints available from the authors at handa@ioa.s.u-tokyo.ac.jp , or the raw TeX (no figures) if you click here.

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