Isotopic signatures of presolar materials in interplanetary dust

Interplanetary dust particles collected in the stratosphere frequently exhibit enrichments in deuterium (D) and N-15 relative to terrestrial materials. These effects are most likely due to the preservation of presolar interstellar materials. While the elevated D/H ratios probably resulted from mass fractionation during chemical reactions at very low < 100 K temperatures, the origin of the N isotopic anomalies remains unresolved. The bulk of the N-bearing material may have obtained its isotopic signatures from low temperature chemistry, but a nucleosynthetic origin is also possible.