The spatial extent and nature of the 3-μm emission features in HD97048 and CPD - 560 8032

Speckle observations at the peaks of narrow dust emission features at 3.3 and 3.5 μm in the low-excitation planetary nebula CPD - 560 8032 and the peculiar emission-line star HD 97048 are presented. In CPD - 560 8032 the emission in the 3.28-μm band is extended on a scale of approx. 1.3 arcsec, and this is probably the same as the extent of the ionized nebula. By contrast, the emission in the 3.53-μm band in HD 97048 is spatially unresolved and arises from a region <0.1 arcsec across. Dust grains within 0.05 arcsec of the star have temperatures > = 1000K, so that the proposed identification of the species emitting the strong 3.43- and 3.53-μm features with formaldehyde ices is untenable, and the materials responsible for the band emission remain unidentified. (author)