Free Access

Fig. A.1


Effect of dust extinction optical depth on the 11.2/3.3 μm ratio. The dust extinction cross-sections per H-atom have been taken from Draine & Li (2001); the model with RV = 5.5). For comparison, the maximum H-column density along the line of sight in the northern PDR of NGC 7023 is measured to be 2.2 × 1021 atoms cm-2 (Fuente et al. 1998).

Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.

Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.

Initial download of the metrics may take a while.