A new observation of C18O (J=1−0) line emission in W31

Using the 13.7-m millimeter wave telescope of Purple Mountain Observatory, we for the first time observed in C18O(J=1−0), the northwest region (size 16′ × 25′) of the molecular cloud W31. We constructed contour maps in different velocity ranges (grid separation 1′). Three compact molecular clumps are identified and their physical parameters are derived from the observed temperature and line width; they are found to be rather young and stable. We discuss their distribution with respect to the associated HII regions, in regard to star formation.