Bayer designation

The Bayer designations are used in astronomy for the systematic naming of stars. They were introduced in 1603 by the German astronomer Johann Bayer in his star atlas Uranometria for many of the brighter stars visible with the naked eye.

The Bayer designation consists of a Greek letter followed by the genitive of the Latin name of the constellation in which the star is, for example, γ Lyrae or ζ Ursae Maiori.

The brightest star seen from us (see also apparent brightness ) of a star image is thereby normally denoted by α, β, etc. the next brightest with examples:

• Brightest star: α ( proper name: Rigil Kentaurus, Toliman )
• Star name by Bayer: α Centauri, abbreviation α Cen

• Third brightest star: γ ( proper name: Alhena )
• Star name by Bayer: γ Geminorum, abbreviation γ Gem

But actually, there are a plurality of constellations for which this order is not met; so take for example, the brightest star in Sagittarius, the terms ε, σ, ζ and δ Sgr, while α and β Sgr look rather insignificant.

The system labeled with Greek letters was later extended, first to Latin lowercase, and then to Latin uppercase. Most of them are rarely used, but there are a few known exceptions such as h Persei, which is in truth is an open star cluster, and P Cygni. The Bayer letters with capital letters did not go beyond that of Q. Today the letter from R are used for identification of variable stars.

A further complication arises from the use of superscript numbers to distinguish between stars with the same letter. Many are double stars, but usually only visually stand together. But there are exceptions, such as the over 8 ° in the sky extending star chain π1, π2, π3, π4, π5 and π6 Orionis, which is the " bow " of Orion.

Two stars carry a double Bayer designation: β Tau / Aur γ and α And / δ Peg. There are also a number of stars whose Bayer designations would assign them to other than normal today constellations due to the reclassification of the official constellation boundaries by the IAU. Nevertheless, this type of naming has been proven and is still widespread today.

For stars for which there is no Bayer designation, it has become, instead, specify the Flamsteed designation.

• Star catalog
• Onomastics