Properties and Kinematics in OMC1 with N2H+ Observations



Using the N2H+ (3-2) observed with the SMA and CSO, and N2H+ (1-0) observed with the NRO 45m and ALMA + IRAM 30m, we study the structure and kinematics of the Orion Molecular Cloud 1 (OMC1). Unlike other molecular lines such as HCO+ or HCN, the observations in N2H+ are less affected by the expansion or explosion originated from the Orion KL, and can trace the dense gas distribution. Using the kinematics and structure, the OMC1 region is divided into three subregions. The northern region consists of multiple filaments parallel with each other, the western region consists of radial filaments, and the southern region is the OMC1-South. These three regions have different velocities, which exhibits a velocity structure similar to a global collapse scenario. We derived the physical parameters of these regions by conducting non-LTE analysis. The high-resolution N2H+ (3-2) and (1-0) images reveal multiple filamentary structure, having a typical width of 0.02-0.03 pc. The non-LTE results show a higher temperature in the eastern part of OMC1, which may be due to external heating from the high mass stars in M42. In addition, we found that the filament regions have a higher density and a lower temperature than the non-filament regions. This may be explained by the blocking of external heating sources due to the dense gas in the filaments. We also study the gas motion inside the filaments, and compare them with the core formation model.