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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.
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]
The Catalogue of Nebulae and Clusters of Stars was first published in 1786 by William Herschel in the Philosophical Transactions of the Royal Society of London. [1] In 1789, he added another 1,000 entries, [2] and finally another 500 in 1802, [3] bringing the total to 2,500 entries. This catalogue originated the usage of letters and catalogue ...
Dating using 206 Pb/ 204 Pb gives an estimated age of 4,566.6 ± 1.0 Ma, [6] matching ages for other chronometers. Another indication of their age is the fact that the abundance of non-volatile elements in chondrites is similar to that found in the atmosphere of the Sun and other stars in our galaxy. [7]
[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 ...
This is a list of links to Abell Catalog of Planetary Nebulae objects. It mostly exist to document which articles exist (which may or maybe not be presumed notable per WP:NASTRO) and to ensure redirects exist if they are not primarily known by their Abell number.
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.
The nebula is known as S 142 in the 1959 Sharpless catalog (Sh2-142). [2] It is extremely difficult to observe visually, usually requiring very dark skies and an O-III filter. The NGC 7380 complex is located at a distance of approximately 8.5 kilolight-years from the Sun , in the Perseus Arm of the Milky Way .