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Ultramafic rocks (also referred to as ultrabasic rocks, although the terms are not wholly equivalent) are igneous and meta -igneous rocks with a very low silica content (less than 45%), generally >18% MgO, high FeO, low potassium, and are composed of usually greater than 90% mafic minerals (dark colored, high magnesium and iron content).
Of the fifty-seven stars included in the new almanac, these two had no traditional names. The RAF insisted that all of the stars must have names, so new names were invented for them. [8] These names have been approved by the IAU WGSN. [2] The book Star Names: Their Lore and Meaning by R. H. Allen (1899) [9] has had effects on star names:
In 2016, the International Astronomical Union (IAU) organized a Working Group on Star Names (WGSN) [2] to catalog and standardize proper names for stars. The WGSN's first bulletin, dated July 2016, [3] included a table of 125 stars comprising the first two batches of names approved by the WGSN (on 30 June and 20 July 2016) together with names of stars adopted by the IAU Executive Committee ...
A mafic mineral or rock is a silicate mineral or igneous rock rich in magnesium and iron. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, and biotite. Common mafic rocks include basalt, diabase and gabbro. Mafic rocks often also contain calcium -rich varieties of plagioclase ...
Astronomical naming conventions. In ancient times, only the Sun and Moon, a few stars, and the most easily visible planets had names. Over the last few hundred years, the number of identified astronomical objects has risen from hundreds to over a billion, and more are discovered every year. Astronomers need to be able to assign systematic ...
Stellar classification. In astronomy, stellar classification is the classification of stars based on their spectral characteristics. Electromagnetic radiation from the star is analyzed by splitting it with a prism or diffraction grating into a spectrum exhibiting the rainbow of colors interspersed with spectral lines.
These accumulations typically occur on the floor of the magma chamber, although they are possible on the roofs if anorthite plagioclase is able to float free of a denser mafic melt. [ 1 ] Cumulates are typically found in ultramafic intrusions , in the base of large ultramafic lava tubes in komatiite and magnesium rich basalt flows and also in ...
The informal names often attributed to other components in a physical multiple (e.g., Fomalhaut B) are treated as unofficial (albeit described as "useful nicknames"), and not included in the List of IAU-approved Star Names. In the List, the components are clearly identified by their identifiers in the Washington Double Star Catalog. [4]