Mid-IR spectral effects of regolith porosity: Implications for surface mineralogy of Trojan asteroids
Abstract
Trojan asteroids are a substantial group of primitive bodies that carry insight into the building blocks that make the larger bodies in our Solar System as well as the formation mechanisms that shaped it. Mid-infrared spectra of Trojans exhibit silicate emission features, not unlike a comet comae. The resemblance between Trojan and comet comae spectra was initially perplexing because asteroid regoliths are optically thick and comet comae are optically thin. To explain this resemblance, researchers hypothesized that Trojan surfaces must consist of a fine-grained, 'fluffy' regolith of silicates or the regolith is made of silicates suspended in a transparent matrix. Few studies have been done to investigate the effect of regolith porosity on silicate features. We found that silicate features, such as the Christiansen feature, decrease in spectral contrast and shift to higher wavelengths with increased regolith porosity. Additionally, the effect of regolith porosity appears to be dependent on grain size. These results have implications for the MIR analysis of any airless body covered in fine-grained silicates.
- Publication:
-
EPSC-DPS Joint Meeting 2019
- Pub Date:
- September 2019
- Bibcode:
- 2019EPSC...13..766M