154 research outputs found

    High-Velocity Molecular Gas in the Galactic Center Radio Lobe

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    We point out a possible association of high-velocity molecular gas with the Galactic Center Radio Lobe (GCL). A molecular spur in the eastern GCL ridge is receding at \Vlsr \sim +100 \kms, and the western spur approaching at \Vlsr \sim -150 \kms, suggesting a high-velocity rotation of the GCL. We study the kinematics of the GCL based on these molecular line data.Comment: To appear in ApJ. Letters, Plain TeX, Figures on reques

    Galactic Center Molecular Arms, Ring and Expanding Shells. II - Expanding Molecular Shell -

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    We investigate the three-dimensional structure of the so-called ``200-pc expanding molecular ring" in the Galactic Center by analyzing (b, Vlsr) diagrams of the 13CO(J=1-0) line emission from the Bell-Telephone Laboratory survey. We show that the b-v features can be fitted by a spheroidal shell pinched at the equator (dumbbell-shaped shell), which we call the expanding molecular shell (EMS). The radius is about 180 pc and the vertical extent is more than +/-50 pc. The shell is expanding at 160 km/s, and is rotating at 70 km/s. The association of the radio continuum emission indicates that the EMS is a mixture of molecular and ionized hydrogen gases. An extended hot (X-ray) plasma appears to fill the interior of the shell. The estimated molecular mass of the shell is approximately 1.E7 Msun and its kinetic energy 2.E54 ergs.Comment: To appear in PASJ vol.47, No.5, 1995, Plain TeX, Figures on reques

    Dark Bulge, Exponential Disk, and Massive Halo in the Large Magellanic Cloud

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    The rotation curve of the Large Magellanic Cloud, which we have derived from high-resolution HI position-velocity diagrams observed by Kim et al (1998), shows a steep central rise and flat rotation with a gradual rise toward the edge. Using the rotation curve, we have calculated the distribution of surface mass density, and show that the LMC has a dark compact bulge, an exponential disk, and a massive halo. The bulge is 1.2 kpc away from the center of the stellar bar, and is not associated with an optical counterpart. This indicates that the "dark bulge" has a large fraction of dark matter, with an anomalously high mass-to-luminosity (M/L) ratio. On the contrary, the stellar bar has a smaller M/L ratio compared to the surrounding regions. (http://www.ioa.s.u-tokyo.ac.jp/~sofue/99lmc.htm)Comment: PASJ 1999 in press, Latex with Postscript figure
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