A Glimpse into the Spectral Variations of CCs and Asteroids

A Glimpse into the Spectral Variations of CCs and Asteroids

The study of carbonaceous chondrites (CCs) provides a unique opportunity to uncover the mysteries of the early Solar system and the evolution of their parent bodies. One powerful tool in deciphering their composition and history lies in their infrared spectral signatures. However, these signatures also pose significant challenges.

Our research focused on analyzing the infrared spectra of 17 CCs, each with distinct characteristics and varying levels of alteration. As we delved deeper into the data spanning 1-25 micron, a fascinating pattern emerged. With increased aqueous alteration, the absorption features at the 3 micron and 6 micron regions intensified and shifted towards shorter wavelengths. These features are indicative of OH-bearing minerals, water molecules, and the emergence of an absorption feature resembling those found in serpentine and saponite minerals.

By comparing laboratory-heated CCs to those naturally altered, we made an intriguing discovery. The OH/H2O absorption feature in the 3 micron region differed depending on whether the CCs were heated to temperatures below or above ~300C. Another significant change we observed was the diminishment of the 12.4 micron/11.4 micron reflectance ratio and a shift in the reflectance peak towards shorter wavelengths in the 9-14 micron range. These alterations can be attributed to the transformation of anhydrous silicates into phyllosilicates.

Moving on to the 15-25 micron region, we uncovered the influence of thermal metamorphism. This phenomenon resulted in the appearance of additional spectral features. The previously observed single reflectance peak at 22.1 micron transformed into two distinct peaks at 19 micron and 25 micron. This shift is primarily caused by the increased presence of anhydrous silicates and olivine recrystallization.

These findings shed new light on the compositions of C-complex asteroids, which are rich in volatiles, as well as the thermal evolution histories of their parent bodies. The ability to analyze the infrared spectra of CCs and asteroids opens up a whole new avenue for understanding the secrets of our Solar system’s early days.

Jinfei Yu, Haibin Zhao, Edward

FAQ:

1. What is the study about?
This study focuses on the analysis of the infrared spectra of carbonaceous chondrites (CCs) to understand the composition and history of the early Solar system and their parent bodies.

2. What were the findings regarding aqueous alteration?
As aqueous alteration increased, the absorption features at the 3 micron and 6 micron regions intensified and shifted towards shorter wavelengths. These features indicate the presence of OH-bearing minerals, water molecules, and the emergence of absorption features resembling serpentine and saponite minerals.

3. What intriguing discovery was made concerning CCs heated to different temperatures?
The OH/H2O absorption feature in the 3 micron region differed depending on whether the CCs were heated to temperatures below or above ~300C. This suggests that heating temperature plays a role in altering the composition of CCs.

4. What changes were observed in the reflectance ratio and peak wavelength?
The reflectance ratio between the 12.4 micron and 11.4 micron wavelengths diminished, and the reflectance peak shifted towards shorter wavelengths in the 9-14 micron range. These changes can be attributed to the transformation of anhydrous silicates into phyllosilicates.

5. What were the findings regarding the 15-25 micron region?
In the 15-25 micron region, the influence of thermal metamorphism was observed. The single reflectance peak at 22.1 micron transformed into two distinct peaks at 19 micron and 25 micron, indicating the increased presence of anhydrous silicates and olivine recrystallization.

Definitions:

– Carbonaceous chondrites (CCs): Meteorites that are rich in carbon compounds, thought to have originated from the early Solar system.
– Infrared spectral signatures: Patterns and characteristics observed in the infrared range of electromagnetic radiation.
– Aqueous alteration: Alterations caused by water, resulting in changes in composition.
– OH-bearing minerals: Minerals containing hydroxyl groups (OH).
– Serpentine and saponite minerals: Specific types of minerals that exhibit certain spectral features.
– Anhydrous silicates: Silicate minerals that do not contain water.
– Phyllosilicates: A group of minerals characterized by the presence of sheets of linked silicate tetrahedra.

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