Cometary Origin of the Zodiacal Cloud and Carbonaceous
The zodiacal cloud is a thick circumsolar disk of small debris particles produced by asteroid collisions and comets. The relative proportion in which these two source populations contribute to the zodiacal cloud and the exact physical mechanism that generates the bulk of observed dust were unknown....
| Main Authors: | , , |
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.246.2257 http://arxiv.org/pdf/0909.4322v1.pdf |
| Summary: | The zodiacal cloud is a thick circumsolar disk of small debris particles produced by asteroid collisions and comets. The relative proportion in which these two source populations contribute to the zodiacal cloud and the exact physical mechanism that generates the bulk of observed dust were unknown. Here we model the IRAS observations of thermal emission from asteroid and cometary particles to explain the origin of the zodiacal cloud. We find that �90 % of the observed mid-infrared emission is produced by particles from the Jupiter-family comets (JFCs). We suggest that spontaneous disruptions of JFCs, rather than the usual cometary activity driven by sublimating volatiles, is the main mechanism that liberates cometary particles into the zodiacal cloud. Our results imply that JFC particles dominate the accretion rate of micrometeorites by Earth. Since their atmospheric entry speeds are typically low (13.9 km s −1 mean), many large JFC grains should survive frictional heating and land on the Earth’s surface. This explains why most antarctic micrometeorites have primitive carbonaceous |
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