Herschel/PACS observations of the 69μm band of crystalline olivine around evolved stars

Context. We present 48 Herschel/PACS spectra of evolved stars in the wavelength range of 67−72 μm. This wavelength range covers the 69 μm band of crystalline olivine (Mg2−2xFe(2x)SiO4). The width and wavelength position of this band are sensitive to the temperature and composition of the crystalline olivine. Our sample covers a wide range of objects: from high mass-loss rate AGB stars (OH/IR stars, Ṁ ≥ 10-5 M⊙/yr), through post-AGB stars with and without circumbinary disks, to planetary nebulae and even a few massive evolved stars.