In astronomy, a variable star designation is a unique identifier given to variable stars. It uses a variation on the

Bayer designation A Bayer designation is a stellar designation in which a specific star is identified by a Greek or Latin letter followed by the genitive form of its parent constellation's Latin name. The original list of Bayer designations contained 1,564 stars. ...

format, with an identifying label (as described below) preceding the Latin

genitive In grammar, the genitive case (abbreviated ) is the grammatical case that marks a word, usually a noun, as modifying another word, also usually a noun—thus indicating an attributive relationship of one noun to the other noun. A genitive can al ...

of the name of the

constellation A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the e ...

in which the star lies. See

List of constellations The following lists of constellations are available: * IAU designated constellations - a list of the current, or "modern", constellations. * Former constellations - a list of former constellations. * Chinese constellations - traditional Chinese ast ...

for a list of constellations and the genitive forms of their names. The identifying label can be one or two Latin letters or a ''V'' plus a number (e.g. V399). Examples are

R Coronae Borealis R Coronae Borealis is a low-mass yellow supergiant star in the constellation of Corona Borealis. It is the prototype of the R Cor Bor class of variable stars, which fade by several magnitudes at irregular intervals. R Coronae Boreali ...

YZ Ceti YZ Ceti is a red dwarf star in the constellation Cetus. Although it is relatively close to the Sun at just 12 light years, this star cannot be seen with the naked eye. It is classified as a flare star that undergoes intermittent fluctuati ...

V603 Aquilae V603 Aquilae (or Nova Aquilae 1918) was a bright nova first observed (from Earth) in the constellation Aquila in 1918. It was the brightest "new star" to appear in the sky since Kepler's Supernova in 1604. Like all novae, it is a binary ...

Naming

The current naming system is: *Stars with existing Greek letter Bayer designations are not given new designations. *Otherwise, start with the letter R and go through Z. *Continue with RR...RZ, then use SS...SZ, TT...TZ and so on until ZZ. *Use AA...AZ, BB...BZ, CC...CZ and so on until reaching QZ, omitting J in both the first and second positions.Most of this system was invented in Germany, which was still on Fraktur at the time, in which the

majuscule Letter case is the distinction between the letters that are in larger uppercase or capitals (or more formally ''majuscule'') and smaller lowercase (or more formally ''minuscule'') in the written representation of certain languages. The writing ...

s "I" and "J" can be difficult to distinguish. *Abandon the Latin script after 334 combinations of letters and start naming stars with V335, V336, and so on. The second letter is never nearer the beginning of the alphabet than the first, e.g., no star can be BA, CA, CB, DA and so on.

History

In the early 19th century few variable stars were known, so it seemed reasonable to use the letters of the Latin script. Because very few constellations contained stars with uppercase Latin-letter Bayer designation greater than Q, the letter R was chosen as a starting point so as to avoid confusion with letter spectral types or the (now rarely used) Latin-letter Bayer designations. Although Lacaille had used uppercase R to Z letters in a few cases, for example X Puppis (HR 2548), these designations were either dropped or accepted as variable star designations. The star T Puppis was accepted by Argelander as a variable star and is included in the General Catalogue of Variable Stars with that designation but is now classed as non-variable. This variable star

naming convention A naming convention is a convention (generally agreed scheme) for naming things. Conventions differ in their intents, which may include to: * Allow useful information to be deduced from the names based on regularities. For instance, in Manhatta ...

was developed by Friedrich W. Argelander. There is a widespread belief according to which Argelander chose the letter R for

German German(s) may refer to: * Germany (of or related to) **Germania (historical use) * Germans, citizens of Germany, people of German ancestry, or native speakers of the German language ** For citizens of Germany, see also German nationality law **Ger ...

''rot'' or

French French (french: français(e), link=no) may refer to: * Something of, from, or related to France ** French language, which originated in France, and its various dialects and accents ** French people, a nation and ethnic group identified with Franc ...

''rouge'', both meaning "red", because many variable stars known at that time appear red. However, Argelander's own statement disproves this. By 1836, even the letter S had only been used in one constellation, Serpens. With the advent of photography the number of variables piled up quickly, and variable star names soon fell into the Bayer trap of reaching the end of the alphabet while still having stars to name. After two subsequent supplementary double-lettering systems hit similar limits, numbers were finally introduced. As with all categories of astronomical objects, names are assigned by the International Astronomical Union (IAU). The IAU delegates the task to the Sternberg Astronomical Institute and the

Institute of Astronomy of the Russian Academy of Sciences The Institute of Astronomy of the Russian Academy of Sciences was known as the Astronomical Council of the Academy of Sciences USSR until 1990. Overview The institute is involved in developing and launching space-based astronomy platforms, and sc ...

in Moscow, Russia. Sternberg publishes the General Catalog of Variable Stars (GCVS), which is periodically (approximately once every two years) amended by the publication of a new "Name-List" of variable stars. For example, in December 2011 the 80th Name-List of Variable Stars, Part II, was released, containing designations for 2,161 recently discovered variable stars; these brought the total number of variable stars in the GCVS to 45,678. Among the newly designated objects were V0654 Aurigae, V1367 Centauri, and BU Coronae Borealis.

Naming

History

See also

References

Further reading