Large-scale mapping of the massive star-forming region RCW38 in the [CII] and PAH emission
Nakagawa, T.; Ojha, D. K.; Fukui, Y.; Onaka, T.; Ghosh, S. K.; Kaneda, H.; Ishihara, D.; Yamagishi, M.; Kondo, T.; Ninan, J. P.; Torii, K.; Hattori, Y.; Tanabe, M.
Japan, India
Abstract
Aims: We investigate the large-scale structure of the interstellar medium (ISM) around the massive star cluster RCW 38 in the [CII] 158 μm line and polycyclic aromatic hydrocarbon (PAH) emission.
Methods: We carried out [CII] line mapping of an area of ~30' × 15' for RCW 38 by a Fabry-Perot spectrometer on a 100 cm balloon-borne telescope with an angular resolution of . We compared the [CII] intensity map with the PAH and dust emission maps obtained by the AKARI satellite.
Results: The [CII] emission shows a highly nonuniform distribution around the cluster, exhibiting the structure widely extended to the north and the east from the center. The [CII] intensity rapidly drops toward the southwest direction, where a CO cloud appears to dominate. We decompose the 3-160 μm spectral energy distributions of the surrounding ISM structure into PAH as well as warm and cool dust components with the help of 2.5-5 μm spectra.
Conclusions: We find that the [CII] emission spatially corresponds to the PAH emission better than to the dust emission, confirming the relative importance of PAHs for photo-electric heating of gas in photo-dissociation regions. A naive interpretation based on our observational results indicates that molecular clouds associated with RCW 38 are located both on the side of and behind the cluster.