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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.
As petrologic type increases from type 3.1 through 3.9, profound mineralogical changes occur, starting in the dusty matrix, and then increasingly affecting the coarser-grained components like chondrules. Type 3.9 chondrites still look superficially unchanged because chondrules retain their original appearances, but all of the minerals have been ...
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]
[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 RCW Catalogue (from Rodgers, Campbell & Whiteoak) is an astronomical catalogue of Hα-emission regions in the southern Milky Way, described in (Rodgers et al. 1960).It contains 182 objects, including many of the earlier Gum catalogue (84 items) objects.
[1] In the second release, some coordinates for southern hemisphere regions have an uncertainty over 1 minute of arc. [1] This can make them difficult to find, so a revised catalog called BFS (Blitz, Fich and Stark) was released [1] with 65 new regions and about 20 removals. [1] Most of the removed items were the aforementioned nebula or ...
[3] In 2006 a classification was published that assigned 7 groups to the primitive achondrites, but the classification remains controversial. The authors define primitive achondrites as meteorites "that exceeded their solidus temperature on the parent body" and thus would partially melt. Meteorites that have been fully melted are included if ...
Many CM chondrules are surrounded by either rims of accessory minerals, or haloes of water-altered chondrule material. [29] [30] The chondrules of CM chondrites, though fewer, are larger than in COs. While CM chondrules are smaller than average in diameter (~300 micrometer), CO chondrules are exceptionally small (~170 um).