Editing Variable-star designation

{{Short description|Unique identifier given to variable stars}}
In [[astronomy]], a '''variable-star designation''' is a unique identifier given to [[variable star]]s.  It extends the [[Bayer designation]] format, with an identifying label (as described below) preceding the [[Latin language|Latin]] [[genitive case|genitive]] of the name of the [[constellation]] in which the star lies. The identifying label can be one or two [[Latin script|Latin]] letters or a ''V'' plus a number (e.g. V399). Examples are [[R Coronae Borealis]], [[YZ Ceti]], [[V603 Aquilae]]. (''See'' [[List of constellations]] ''for a list of constellations and the genitive forms of their names''.)

==Naming==
The current naming system is:<ref name=levy/>
* 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.
* After ZZ return to the beginning of the Latin alphabet and use AA–AZ, BB–BZ, CC–CZ, and so on, until reaching QZ, but omitting the letter&nbsp;J in either first or second position.{{efn|
Most of this system was invented in [[Germany]], which was still on [[Fraktur (typeface sub-classification)|Fraktur]] at the time, in which the [[majuscule]]s "I" and "J" can be difficult to distinguish.
}}
* Abandon the Latin letters after all 334&nbsp;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&nbsp;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 Carinae|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 [[Nicolas Louis de Lacaille|Lacaille]] had used uppercase R–Z&nbsp;letters in a few cases, for example X&nbsp;Puppis (HR&nbsp;2548), these designations were either dropped or accepted as variable star designations.<ref name=wagman/> The star T&nbsp;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.<ref name=coelum/>

This variable star [[Astronomical naming conventions|naming convention]] was developed by [[Friedrich Wilhelm Argelander|Friedrich W. Argelander]]. There is a widespread belief according to which Argelander chose the letter&nbsp;R for [[German language|German]] ''rot'' or [[French language|French]] ''rouge'', both meaning "red", because many variable stars known at that time appear red.<ref name=chapman/> However, Argelander's own statement disproves this.<ref name=cds/>

By 1836, even the letter&nbsp;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.{{citation needed|date=April 2020}} After two subsequent supplementary double-lettering systems hit similar limits, numbers were finally introduced.<ref name=cds/>

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]] in Moscow, Russia. Sternberg publishes the ''General Catalog of Variable Stars'' ({{sc|GCVS}}), which is amended approximately once every two years by the publication of a new ''Name-List of Variable Stars''.<ref name=sternberg/> For example, in December&nbsp;2011, the 80th ''Name-List of Variable Stars'', Part&nbsp;II, was released, containing designations for 2,161&nbsp;recently discovered variable stars, which brought the total number in the {{sc|GCVS}} to 45,678&nbsp;variable stars. Among the newly designated objects were V0654&nbsp;Aurigae, V1367&nbsp;Centauri, and BU&nbsp;Coronae Borealis.<ref name=namelist/>

== Footnotes ==
{{notelist|199em}}

== See also ==
* [[star catalogue]]
* [[star designation]]

== References ==
{{reflist|25em|refs=

<ref name=cds>
{{cite report
 |title=The names and catalogues of variable stars
 | publisher = [[University of Strasbourg]]
 | place = Strasbourg, FR
 |url=http://cdsarc.u-strasbg.fr/afoev/var/edenom.htx
 |via=cdsarc.u-strasbg.fr
 |access-date=2018-11-16
}}
</ref>

<ref name=chapman>
{{cite journal
 |last=Chapman |first=David M.F.
 |year=1999
 |title=Reflections: F.W.A. Argelander - ''Star Charts and Variable Stars''
 |journal=[[Journal of the Royal Astronomical Society of Canada]]
 |volume=93 |pages=17
 |bibcode=1999JRASC..93...17C
}}
</ref>

<ref name=coelum>
{{cite book
 |first=Nicolas-Louis |last=de la Caille |author-link=Nicolas-Louis de Lacaille
 |year=1763
 |title=Coelum australe stelliferum
 |publisher=Hipp. Lud.Guerin & Lud. Fr. Delatour
 |url=https://books.google.com/books?id=ijEVAAAAQAAJ
 |via=Google
}}
</ref>

<ref name=levy>
 {{cite book
 |first=D.H. |last=Levy |author-link=David H. Levy
 |date=15 December 2005
 |title=''David Levy's'' Guide to Variable Stars
 |publisher=Cambridge University Press
 |isbn=978-0-521-60860-2
 |page=46&nbsp;ff
 |url=https://books.google.com/books?id=Df9d8FBagqEC&pg=PA46
}}
</ref>

<ref name=namelist>
{{cite journal
 |first1 = E.V. |last1 = Kazarovets
 |first2 = N.N. |last2 = Samus
 |first3 = O.V. |last3 = Durlevich
 |first4 = N.N. |last4 = Kireeva
 |first5 = E.N. |last5 = Pastukhova 
 |collaboration = GCVS Research Group
 |display-authors = etal
 |year=2013
 |title=Novae in the 80th ''Name-list of Variable Stars'' (Part 3): Official announcement of {{sc|GCVS}} names
 |journal=Peremennye Zvezdy [Variable Stars]
 |volume=33 |issue=3 |pages=3
 |bibcode=2013PZ.....33....3K
 |ISSN=2221-0474  |type=online-only journal
}}
</ref>

<ref name=sternberg>
{{cite web
 |first1 = N.N. |last1 = Samus
 |first2 = E.V. |last2 = Kazarovets
 |first3 = O.V. |last3 = Durlevich
 |first4 = N.N. |last4 = Kireeva
 |first5 = E.N. |last5 = Pastukhova 
 |collaboration = GCVS Research Group
 |display-authors = etal
 |date = c. 1998
<!-- moved into author list ---
 |editor-last = Durlevich  |editor-first = Olga
-->
 |title = GCVS Research Group: History and persons
 |publisher = [[Sternberg Astronomical Institute]] 
 |place = Moscow, RU
 |quote = International service of variable stars: Naming, classification, identification
 |url = http://www.sai.msu.ru/gcvs/intro.htm
 |via = sai.msu.ru
 |access-date = 2018-11-16
}}
</ref>

<ref name=wagman>
{{cite book
 |first=Morton |last=Wagman
 |year=2003
 |title=Lost Stars: Lost, missing, and troublesome stars from the catalogues of Johannes Bayer, Nicholas-Louis de la Caille, John Flamsteed, and sundry others
 |pages={{mvar|viii}}, 540
 |publisher=McDonald & Woodward Publishing
 |isbn=978-0-939923-78-6
 |bibcode=2003lslm.book.....W
 |url=https://books.google.com/books?id=TYLvAAAAMAAJ
}}
</ref>

}} <!-- end "refs=" -->

== Further reading ==
{{refbegin|25em|small=yes}}
* {{cite report
 |last1=Samus     |first1=N.N.
 |last2=Durlevich |first2=O.V.
 |display-authors=etal
 |year=2009
 |title=''General Catalogue of Variable Stars'' ({{sc|GCVS}})
 |department=(Samus+ 2007-2013)
 |website=VizieR On-line Data Catalog
 |series=B/{{sc|gcvs}} |volume=1 
 |type=online database
 |bibcode=2009yCat....102025S
}} {{nobr|Original publication {{bibcode|2009yCat....102025S}} }}

* {{cite report
 | title = The names and catalogues of variable stars
 | series = Les étoiles variables [The variable stars]
 | publisher = [[University of Strasbourg]]
 | place = Strasbourg, FR
 | url=http://cdsweb.u-strasbg.fr/afoev/var/edenom.htx
 | via=cdsweb.u-strasbg.fr
 | access-date=2005-11-06
}}
{{refend}}

[[Category:Variable stars|designation]]
[[Category:Stellar astronomy]]
[[Category:Objects with variable star designations| ]]