Inherited material from the protosolar cloud: composition and origin

When the most primitive types of meteorite, the chondrites, formed, all of them incorporated small amounts of at least two types of unprocessed pre-solar material: interstellar organic matter and circumstellar grains. The organic matter formed in the protosolar molecular cloud. To date, six types of circumstellar grain have been identified and their isotopic compositions show that they formed around red giant/asymptotic giant branch (RGB/AGB) stars, supernovae and, possibly, novae and Wolf-Rayet stars.