FCRAO CO Survey of the Outer Galaxy

While comprising only a small fraction of the volume of the interstellar medium, molecular clouds are an important component since these are the sites of star formation within the Galaxy. Large scale, unbiased surveys are required to determine the distribution of molecular material within the Galaxy and to statistically evaluate cloud properties from which the appropriate physics can be applied. However, previous surveys of the CO J=1-0 emission, the primary tracer of molecular hydrogen, from the first quadrant of the Galaxy have been limited by the blending of emission from unrelated clouds due to Galactic rotation.

The Five College Radio Astronomy Observatory has completed an ambitious survey to image CO J=1-0 emission from the second quadrant of the Galaxy where such cloud blending is absent The survey covers 330 square degrees at 50 arcsec sampling using the 15 element focal plane array receiver QUARRY. The data provides unprecedented information to address fundamental questions of the molecular interstellar medium and galactic structure. These include the large scale topology of the molecular component, the enhancement of molecular gas surface density within spiral arms, and the mostly unexplored relationship between the molecular and atomic gas components.

The following image shows the distribution of peak CO antenna temperature within the velocity interval -105 to 5 km/sec measured from 1,696,800 spectra!

Image of integrated 12CO emission from the outer Galaxy

Image of integrated 12CO emission from the outer Galaxy taken with the FCRAO 14m telescope and QUARRY.

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Publications from the Survey:

  • '' A Massive Cometary Cloud Associated with IC 1805 ''
    1996, ApJ, 464, L175
  • ''A Massive Cometary Cloud Associated with IC 1805: Erratum''
    1996, ApJ, 464, L139
  • ''The Five College Radio Astronomy Observatory CO Survey of the Outer Galaxy''
    1998, ApJS, 115, 241
  • ''The Anatomy of the Perseus Spiral Arm: 12CO and IRAS Imaging Observations of the W3-W4-W5 Cloud Complex''
    1998, ApJ, 502, 265
    A listing of the cloud catalog used in this paper is available by clicking here
  • ''On the Fractal Structure of Molecular Clouds''
    1998, AA, 336, 697
  • ''JCMT Observations of Molecular Clouds in the Galactic Chimney Near W4''
    1999, ApJ, 513, 339
  • ''Embedded Stellar Clusters in the W3/W4/W5 Molecular Cloud Complex''
    2000, ApJS, 130, 381
  • ''The HII Region KR 140: Spontaneous Formation of a High Mass Star''
    2000, ApJ, 539, 283
  • ''A New View of Cold HI Clouds in the Milky Way''
    2000, ApJ, 540, 851
  • '' The Equilibrium State of Molecular Regions in the Outer Galaxy''
    2001, ApJ, 551, 852
  • ''GSH 138-01-94: An Old Supernova Remnant in the Far Outer Galaxy''
    2001, ApJ, 563, 816
  • ''The Supernova Remnant CTB 104A: Magnetic Field Structure and Interaction with the Environment''
    2002, ApJ, 565, 1022
  • ''Interstellar Turbulence: I. Retrieval of Velocity Field Statistics''
    2002, ApJ, 566, 276
  • ''Interstellar Turbulence: II. Energy Spectra of Molecular Regions in the Outer Galaxy''
    2002, ApJ, 566, 289
  • ''Infrared Clusters in the Far-Outer Galaxy''
    2002, ApJ, 578, 229
  • ''Molecular Cloud Distances via Principal Component Analysis''
    2002, ApJ, 567 L41
  • ''The Distance to Supernova Remnant CTB 109 Deduced from Its Environment''
    2002, ApJ, 576, 169
  • ''Detecting Embedded Intermediate-Mass Stars Using Mid-Infrared and H I 21 Centimeter Emission''
    2002, AJ, 124, 3449
  • ''An Outer Galaxy Molecular Cloud Catalog''
    2003, ApJS, 144, 47
  • ''Large-Scale Turbulence in Molecular Clouds''
    2003, ApJ, 583, 280
  • ''The Universality of Turbulence in the Molecular Interstellar Medium and Its Exploitation as a Distance Estimator''
    2003, ApJ, 584, 293
  • ''The association of IRAS sources and 12CO emission in the outer Galaxy''
    2003, AA, 399, 1083
  • ''Large-Scale Structure and Dynamics of Cassiopeia OB7''
    2003, AJ, 125, 2050
  • Download Survey Data

    The Survey is available as a series of two dimensional velocity-longitude images at the following archive centers.

    NCSA Astronomy Digital Image Library

  • On the QUERY page , be sure to include the survey filter in the search.
  • To get the data by Codename use the codeword: 97.MH.01

    NASA Astronomical Data Center

    Back to the FCRAO Home Page.

    Last Modified : Wednesday, 22-Jan-97 16:25:59 EST