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A. M. Johnson, J. M. Rathborne, J. M. Jackson, R. Y. Shah (Boston University), R. Simon (Universitat zu Koeln)
The Boston University--Five College Radio Astronomy Observatory (BU-FCRAO) Galactic Ring Survey (GRS) is a new survey of 13CO (1--0) emission covering Galactic longitudes 18 deg < l < 55.7 deg and Galactic latitudes |b| < 1 deg. Using the SEQUOIA array on the FCRAO 14m telescope, the GRS fully sampled the 13CO Galactic emission (46 arcsec angular resolution on a 22 arcsec grid) and achieved a spectral resolution of 0.21 kms-1. By using 13CO, a better column density tracer than the more commonly used 12CO, the GRS allows a much better determination of column density and also a cleaner separation of velocity components along a line of sight. Thus, the GRS detects many new structures and cloud cores previously missed by the older 12CO surveys.
With this homogeneous, fully-sampled survey of 13 CO emission, we can identify and catalog molecular clouds throughout the inner Galaxy. To select molecular clouds, we use the CLUMPFIND algorithm, which uses a method of closed contours to search for contiguous emission features without assuming an a priori shape. The molecular cloud catalog will allow us to characterize the masses, sizes, line-widths, and densities of molecular clouds in a range of Galactic environments. This will also allow us to determine clump mass spectra for many molecular complexes and study its relation to the initial mass function. In addition, the internal structure of molecular clouds, which traces the influence of turbulence in the interstellar medium, can also be studied in a wide range of star-forming environments. Here we present a preliminary list and analysis of the characteristics of a sample of molecular clouds identified within the GRS.
The GRS is a joint project of Boston University and Five College Radio Astronomy Observatory, funded by the National Science Foundation under grants AST-9800334, AST-0098562, & AST-0100793
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Bulletin of the American Astronomical Society, 37 #4
© 2005. The American Astronomical Soceity.