Multifield Mosaic of the NGC 7538 Region

We present mosaics of six Very Large Array images made in the NH 3 (1, 1) and (2, 2) lines toward NGC 7538. Both the NH 3 (1, 1) and (2, 2) emissions show clumpy and filamentary structures. The dense clumps are found near water maser emission or near the youngest member of groups of infrared sources. At the edges of clumps, temperature enhancements indicate external heating possibly by the nearby H II regions. The outflows in this region are conspicuously located in the voids between the clumps. Because there is more mass in the dense clumps than in the outflows, we suggest that the dense medium shapes the outflows and channels the swept-up material to the low-density regions.