Bayer name
The Bayer designation is used in astronomy for the systematic naming of stars used. It is named after the German astronomer Johann Bayer .
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The Bayer name consists of a Greek letter followed by the genitive of the Latin name of the constellation in which the star is located, e.g. B. γ Lyrae (“Gamma” + genitive from “ Lyra ”) or ζ Ursae Maioris (“Zeta” + genitive from “ Ursa Major ”).
From our point of view, the brightest star (see also Apparent brightness ) of a constellation is usually denoted by α, the next brightest by β, etc.
Examples:
- Constellation: Centaurus (Centaur)
- brightest star: α (" Alpha ", first letter of the Greek alphabet)
- Star name according to Bayer: α Centauri ("Alpha Centauri"), abbreviation: α Cen
- Proper names: Rigil Kentaurus, Toliman
- Constellation: Gemini (Gemini)
- third brightest star: γ (" Gamma ", third letter of the Greek alphabet)
- Star name according to Bayer: γ Geminorum ("Gamma Geminorum"), abbreviation: γ Gem
- Proper name: Alhena
In fact, there are a large number of constellations in which this order is not kept; For example, the brightest stars in Sagittarius are labeled ε, σ, ζ and δ Sgr, while α and β Sgr seem rather inconspicuous.
The system of designation with Greek letters was later expanded, first with Latin lowercase letters and then with Latin uppercase letters. Most of them are rarely used, but there are a few known exceptions such as h Persei , which is actually an open star cluster , and P Cygni . The Bayer names with capital letters did not go beyond Q. Today the letters from R are used to denote variable stars .
Another complication arises from the use of superscript numbers to distinguish stars with the same letter. Many of them are double stars , but most of them only appear together. But there are also exceptions such as the star chain π 1 , π 2 , π 3 , π 4 , π 5 and π 6 Orionis , which extends over 8 ° in the sky , which forms the "arch" of Orion .
Two stars have a double Bayer designation: β Tau / γ Aur and α And / δ Peg . In addition, due to the official redistribution of the constellation boundaries by the IAU, there are a number of stars whose Bayer designations you would assign to other constellations than the conventional ones today. Nevertheless, this type of naming has proven itself and is still widely used today.
history
Johann Bayer introduced this designation in 1603 in his star atlas Uranometria , whereby he only considered lighter stars visible to the naked eye in Europe. Southern constellations, which are almost or not at all visible in Europe, were not given a name. In addition, during Bayer's lifetime the constellations were not yet defined as adjacent areas, so there were gaps between them, mostly with faint stars.
In the course of time these gaps were filled with new constellations, e.g. B. by Johannes Hevelius in his catalog Prodromus astronomiae published posthumously in 1690 . It is not known whether he gave the stars inside with a Bayer designation, at least they do not appear in this catalog.
In 1845 the British astronomer Francis Baily published his British Association's Catalog . According to his own statements, he gave numerous names to the brighter stars of the new constellations. So there are z. B. for the constellation Octant at the celestial south pole a whole series from Alpha Octantis to Omega Octantis .
Nowadays the constellations are only of minor importance as asterisms in astronomy and thus the Bayer names are also losing importance. With a few exceptions, all stars with Bayer designation can be found in the Bright Star catalog , which enables modern referencing.