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Chondrules in the chondrite classification Grassland. A millimeter scale is shown. Chondrules in the Carbonaceous Chondrite NWA 13887. A chondrule (from Ancient Greek χόνδρος chondros, grain) is a round grain found in a chondrite. Chondrules form as molten or partially molten droplets in space before being accreted to their parent asteroids.
Primitive achondrites are a subdivision of meteorites.They are classified on the same rank (historically called "Class") and lying between chondrites and achondrites.They are called primitive because they are achondrites that have retained much of their original chondritic properties.
A chondrite / ˈ k ɒ n d r aɪ t / is a stony (non-metallic) meteorite that has not been modified by either melting or differentiation of the parent body. [a] [1] They are formed when various types of dust and small grains in the early Solar System accreted to form primitive asteroids.
Aqueous alteration promotes a composition of hydrous phyllosilicates, magnetite, and olivine crystals occurring in a black matrix, and a possible lack of chondrules. It is thought they have not been heated above 50 °C (122 °F), indicating that they condensed in the cooler outer portion of the solar nebula.
[1] [4] Entries in the catalogue are designated with a "C" and the catalogue number (1 to 109). Unlike objects in the Messier catalogue, which are listed roughly in the order of discovery by Messier and his colleagues, [ 5 ] the Caldwell catalogue is ordered by declination , with C1 being the most northerly and C109 being the most southerly ...
The main petrologic characteristic of Type 1 chondrites, such as CIs, is the lack of recognizable chondrules, thus excepting the sample from Tagish Lake. Yet small chondrule fragments and calcium–aluminium-rich inclusions (CAIs) do occur, but are quite rare.
While CM chondrules are smaller than average in diameter (~300 micrometer), CO chondrules are exceptionally small (~170 um). [ 31 ] [ 32 ] This may be a survivor bias : consider that the water which dissolves CM chondrules successfully eliminates those which are already small, while those which were large may remain to be observed, though with ...
The nebulae listed by Barnard have become known as Barnard objects. [2] A 1919 version of the catalogue listed 182 nebulae; [3] by the time of the posthumously published 1927 version, it listed 369. [4] Barnard's niece and assistant Mary Ross Calvert, also an astronomer and astrographer, took an important part in creating the catalogue. [5]