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We present the results of mapping observations toward an outflow-shockedregion, OMC-2 FIR 4 using the Nobeyama 45-m telescope. We observed the area in$^{13}$CO ($J=1-0$), C$^{18}$O ($J=1-0$), N$_2$H$^+$ ($J=1-0$), CCS($J_N=8_7-7_6$), HCO$^+$ ($J=1-0$), H$^{13}$CO$^+$ ($J=1-0$), HN$^{13}$C($J=1-0$), H$^{13}$CN ($J=1-0$), DNC ($J=1-0$), N$_2$D$^+$ ($J=1-0$), andDC$_3$N ($J=9-8$). We detected a dense molecular clump that contains FIR 4/5.We also detected in $^{13}$CO blueshifted and redshifted components drivenpresumably by protostellar outflows in this region. The axes of the FIR 3 andVLA 13 outflows, projected on the plane of the sky, appear to point toward theFIR 4 clump, suggesting that the clump may be compressed by protostellaroutflows from Class I sources, FIR 3 and VLA 13. Applying the hyperfine fit ofN$_2$H$^+$ lines, we estimated the excitation temperature to be $\sim$ 20 K.The high excitation temperature is consistent with the fact that the clumpcontains protostars. The CCS emission was detected in this region for the firsttime. Its abundance is estimated to be a few $\times 10^{-12}$, indicating thatthe region is chemically evolved at $\sim 10^5$ years, which is comparable tothe typical lifetime of the Class I protostars. This timescale is consistentwith the scenario that star formation in FIR 4 is triggered by dynamicalcompression of the protostellar outflows. The [HNC]/[HCN] ratio is evaluated tobe $\sim 0.5$ in the dense clump and the outflow lobes, whereas it is somewhatlarger in the envelope of the dense clump. The small [HNC]/[HCN] ratioindicates that the HNC formation was prevented due to high temperatures. Suchhigh temperatures seem to be consistent with the scenario that eitherprotostellar radiation or outflow compression, or both, affected the thermalproperties of this region.

Nobeyama 45-m Mapping Observations toward Orion A. III. Multi-Line Observations toward an Outflow-shocked Region, OMC-2 FIR