(Proposal ID) S13B-013 (PI) Ohsawa, Ryou (Proposal Title) Investigation of the PAH size distribution in a compact HII region (Abstract) Polycyclic aromatic hydrocarbons (PAHs) are excited by absorbing UV photons and emit the strong emission features in the infrared. The PAH emission features can be a good estimator of star formation rates (SFRs). On the other hand, PAHs are destroyed in harsh environments like HII regions. Two mechanisms are suggested for PAH destruction; sputtering and photo- dissociation. It is not observationally investigated which process is dominant in HII regions. We invent a method to identify the dominating destruction process in terms of the size distribution of PAHs. We propose the near- infrared imaging observations of a compact HII region M1-78 with the Gemini/ NIRI. We investigate the variation in the PAH size distribution in M1-78 and discuss which destruction process is dominant in HII regions.