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11:34
Scattering And Absorption of Light in Planetary Regoliths
Published on: July 1, 2019
Chemically anomalous, preaccretionally irradiated grains in interplanetary dust from comets
Science (New York, N.Y.)
|August 12, 1994
Summary
Interstellar dust grains found in comets show chemical anomalies from radiation exposure. These findings suggest that such anomalies can identify presolar interstellar components in meteoritic materials.
Area of Science:
- Cosmochemistry
- Planetary Science
- Astrobiology
Background:
- Interplanetary dust particles (IDPs) offer insights into solar system formation.
- Cometary dust contains primitive materials that may preserve presolar components.
Purpose of the Study:
- To investigate the origin and nature of nonstoichiometric grains in cometary IDPs.
- To determine if chemical anomalies in these grains are indicative of an interstellar origin.
Main Methods:
- Analysis of chemical composition of grains within cometary IDPs.
- Comparison of grain characteristics with known interstellar dust properties.
- Assessment of radiation effects on grain chemistry.
Main Results:
- Identified nonstoichiometric grains (GEMS) with depletions in Mg and Si and inclusions of Fe-Ni metal and sulfides.
- Observed chemical anomalies consistent with accumulation from ionizing radiation exposure.
- Inferred exposure ages, sizes, and structures align with interstellar silicate grains.
Conclusions:
- GEMS in cometary IDPs likely originated in interstellar space.
- Chemical and isotopic anomalies serve as reliable tracers for presolar interstellar components in primitive meteorites.
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