SiC and Iron Rich Grains in Cometary Dust

摘要

Elemental and isotopic abundances in cometary dust, as measured by the mass spec-trometers PUMA/Vega and PIA/Giotto in comet Halley, show similar bulk compo-sition as CI chondrites (Jessberger et al., 1989). Most of the cometary dust grainsare complex conglomerates of more mineral species, usually mixed with some organicstuff. However, chemically homogenous material can be expected in very small grains.In the search for such particles in PUMA 1 archive several mass spectra with onlyfew features were found. The total number of ions in those spectra was low and thusthe masses of the corresponding grains were only sligthly above the lower limit of theinstrumental mass range (femtogramms).