The HII Region W40 and its Molecular Cloud
Extensive new and published older observations of the HII region W40 and its associated molecular cloud have been analyzed. The HII region is near the center of an extensive dark cloud which is contracting at 3 km/s along the line of sight. The HII region is adjacent to the high-density, warm core of the molecular cloud and is responsible for heating it. The ionized hydrogen is expanding away from the high-density molecular gas at velocities up to 8 km/s and is just beginning to break through holes in the near side of the dark cloud.
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