C^18^O dense cores in Orion A molecular cloud

Applying dendrogram analysis to the CARMA-NRO Orion C^18^O (J=1-0) data, we identify 2342 dense cores, about 22% of which have virial ratios smaller than 2 and can be classified as gravitationally bound cores. The derived core mass function (CMF) for bound starless cores that are not associate with protostars has a slope similar to Salpeter's initial mass function (IMF) for the mass range above 1M_{sun}_, with a peak at ~0.1M_{sun}_.

We divide the cloud into four parts based on decl., OMC-1/2/3, OMC-4/5, L1641N/V380 Ori, and L1641C, and derive the CMFs in these regions. We find that starless cores with masses greater than 10M_{sun}_ exist only in OMC-1/2/3, whereas the CMFs in OMC-4/5, L1641N, and L1641C are truncated at around 5-10M_{sun}_. From the number ratio of bound starless cores and Class II objects in each subregion, the lifetime of bound starless cores is estimated to be 5-30 freefall times, consistent with previous studies for other regions.