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Designations of stars (and other celestial bodies) is mediated by the International Astronomical Union (IAU). Many of the star names in use today were inherited from the time before the IAU existed. Other names, mainly for variable stars (including novae and supernovae), are being added all the time. Approximately 10,000 stars are visible to the naked eye.〔Under average conditions, about 5,600 stars brighter than magnitude +6 are visible to the naked eye; theoretically, under perfect conditions, about 45,000 stars brighter than magnitude +8 would be visible.〕 Pre-modern catalogues listed only the brightest of these. Hipparchus in the 2nd century BC enumerated about 850 stars. Johann Bayer in 1603 listed about twice this number. Only a minority of these have proper names; all others are designated by numbers from various catalogues. Only in the 19th century did star catalogues list the naked-eye stars exhaustively. The most voluminous modern catalogues list of the order of a billion stars, out of an estimated total of 200 to 400 billion in the Milky Way. == Proper names == (詳細はbrightest stars have traditional names, most of which derive from Arabic, but a few from Latin.〔The NASA in 1971 compiled a "technical memorandum" collecting a total of 537 named stars. (Rhoads, J. W.,''Technical Memorandum 33-507 – A Reduced Star Catalog Containing 537 Named Stars'', NASA-CR-124573 (1971). ) 〕 There are a number of problems with these names, however: * Spellings are often not standardized (Almach or Almaach or Almak or Alamak) * Many stars have more than one name of roughly equal popularity (Mirfak or Algenib or Alcheb; Regor or Suhail al Muhlif; Alkaid or Benetnasch; Gemma or Alphecca; Alpheratz and Sirrah) * Because of imprecision in old star catalogs, it may not be clear exactly which star within a constellation a particular name corresponds to (e.g., Alniyat can refer to Sigma Scorpii or Tau Scorpii, Chara). * Some stars in entirely different constellations may have the same name: Algenib in Perseus and Algenib in Pegasus; Gienah in Cygnus and Gienah in Corvus, Alnair in Grus and Alnair in Centaurus. In practice, the traditional names are only universally used for the very brightest stars (Sirius, Arcturus, Vega, etc.) and for a small number of slightly less bright but "interesting" stars (Algol, Polaris, Mira, etc.). For other naked eye stars, the Bayer designation is often preferred. In addition to the traditional names, a small number of stars that are "interesting" can have modern English names. For instance Barnard's star has the highest known proper motion of any star and is thus notable even though it is far too faint to be seen with the naked eye. See stars named after people. Two second-magnitude stars, Alpha Pavonis and Epsilon Carinae, were assigned the proper names Peacock and Avior respectively in 1937 by Her Majesty's Nautical Almanac Office during the creation of The Air Almanac, a navigational almanac for the Royal Air Force. Of the fifty-seven stars included in the new almanac, these two had no classical names. The RAF insisted that all of the stars must have names, so new names were invented for them. The book ''Star Names: Their Lore and Meaning'' by R.H.Allen (1899) has had effects on star names: *It lists many Assyrian/Babylonian and Sumerian star names recovered by archaeology, and some of these (e.g. Sargas and Nunki) have come into general use. *It lists many Chinese star names (e.g. Cih alias Tsih), though these have not come into general usage. *R.H.Allen represented the "kh" sound by 'h' with a dot above (ḣ), and at least one astronomy book (a book by Patrick Moore) using R.H.Allen as a source, has misread this unfamiliar letter as 'li'. A few stars are named for individuals. These are mostly unofficial names that became official at some juncture. The first such case (discounting characters from Greek mythology) was Cor Caroli (α CVn), named in the 17th century for Charles I of England. The remaining examples are mostly stars named after astronomers or astronauts. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Stellar designation」の詳細全文を読む スポンサード リンク
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