Dynamics Within Carina's Irradiated Western Wall
In order to quantify how a molecular cloud responds on subarcsecond scales when subjected to a powerful radiation front in a region of massive star formation we have acquired high-resolution ALMA maps of the continuum and 12CO, 13CO, C18O, and CI line emission in a portion of Carina's iconic Western Wall (G287.38-0.62; Car 1-E), situated near Trumpler 14 and well-known as the brightest H2-fluorescence source in the region. In addition to clearly demonstrating the physics within a PDR front, these data allow us to separate the Wall from foreground and background clouds. Within the Wall we identify coherent gas 'droplets' on small scales and compare their mass and virial distributions with those of cores located in less-irradiated environments. The observations are ideal for studies of turbulence, and make it possible to investigate correlation lengths and driving scales. There is no direct evidence for triggering of star formation in the Western Wall in that its C18O clumps and continuum cores appear starless, with no pillars present. However, radiation helps create conditions more suitable for star formation, in that the densest portion of the cloud lies closest to the PDR, and the C18O emission flattens along the radiation front.
