Presentation #114.09 in the session “High-mass Star Formation”.
We present the observational evidences of Cloud-Cloud Collision (CCC) in Orion A. The kinematic properties of young stellar objects (YSOs) as well as cold and warm interstellar medium have been studied by utilizing SDSS IN-SYNC near-infrared spectra, CARMA-NRO 13CO(1-0) emission, and SOFIA-upGREAT 158μm [CII] emission data of Orion A. We investigate the kinematic correlation of YSOs and ambient gas via comparing the near-infrared YSO spectra vs. 13CO(1-0) emission. The correlation between the cold ambient dense medium and warm envelope is examined via analyzing the 13CO(1-0) and the [CII] emissions. Using theoretical models, we find that the northern part of Orion A, including regions ONC-OMC-1, OMC-2, OMC-3 and OMC-4, shows qualitative agreements with the CCC scenario while in one of the southern regions, NGC1999, there is no indication of such a process for the star cluster formation. The analytical trends of another southern cluster, L1641N, show slight tendencies of CCC. Overall, our results favor the scenario of CCC and support it to be a potential major mechanism for the star cluster formation in Orion A cloud.