FWHM of the forsterite “69 μm band” plotted over the peak position, fitted with a Lorentz profile. The red squares with error bars represent measurements taken from our PACS observations. The numbers refer to the stars as follows: (0) HD 100546, (1) HD 104237, (2) AB Aur, (3) HD 141569, (4) HD 179218, (5) IRS 48, (6) HD 144668, (7) AS 205. The green asterisks are taken from Koike et al. (2003) and the blue crosses are based on Suto et al. (2006), computed with the DHS model (Min et al. 2003) and a grain size of 0.1 μm. The black arrow indicates the temperature dependency.