CAIs, IDPs, & GEMs

Calcium-aluminum-rich inclusions (CAIs), found in chondritic meteorites, are the oldest-known objects formed in the infant solar nebula. They preserve clues to the chemical processes and environments that existed during their formation in the nebula phase of the Solar System, which was extremely hot and reducing leading to a volatility-controlled elemental composition. The isotopic compositions of CAIs retain some presolar components which can indicate their nucleosynthetic origin. The CHILI Lab has collaborated with researchers at the Smithsonian to analyze the isotopic compositions of CAIs in order to better understand the major processes that accompanied the formation of the Sun and the solar nebula.

(Source: MacPherson et al.)

Remnants from the formation of the Solar System exist in the form of interstellar dust, sitting in our galactic neighborhood. Similarly, interplanetary dust (IDPs), shed by passing comets, can provide information on the processes that occurred during Solar System formation. Sampling from these reservoirs uncovers the identities of the typical feedstock of the planets, revealing our cosmic roots. Characterizing interstellar dust enables the determination of the raw materials that were present during the formation of the solar system and resolves conflicting information about its makeup and size distribution from optical starlight observations, Ulysses and Cassini in situ measurements, and laboratory analysis of Stardust samples. Interplanetary dust samples can be used to determine the degree to which the material in comets was processed by heat and water in the early solar system and to characterize organics delivered by comets to the planets.

(Source: Horányi et al.)

The CHILI Lab has been involved in analyzing GEMS and comparing the isotopic composition with amorphous silicates found in meteorites. GEMS are unique grains found in large quantities within IDPs. These grains are typically under 0.5 micrometers in diameter and are composed of subgrains made from FeNi metal and sulfides within an amorphous Mg-Fe-Al silicate matrix. Their importance comes from their abundance in IDPs, suggesting they are a significant building block in the early Solar System. However, the origin of GEMS is unknown, with two major hypotheses that are fueled by the grain-size limitations in isotopic measurements: