Editing Binary star (section)

==Designations==
===A and B===
[[File:This artist’s impression shows the strange object AR Scorpii.jpg|thumb|Artist's impression of the binary star system [[AR Scorpii]]]]
The components of binary stars are denoted by the suffixes ''A'' and ''B'' appended to the system's designation, ''A'' denoting the primary and ''B'' the secondary. The suffix ''AB'' may be used to denote the pair (for example, the binary star α Centauri AB consists of the stars α Centauri A and α Centauri B.) Additional letters, such as ''C'', ''D'', etc., may be used for systems with more than two stars.<ref name=Heintz19>{{cite book | last=Heintz | first=W. D. | date=1978 | page=[https://archive.org/details/DoubleStars/page/19 19] | title=Double Stars | publisher=D. Reidel Publishing Company | location=Dordrecht | isbn=978-90-277-0885-4 | url=https://archive.org/details/DoubleStars/page/19 }}</ref> In cases where the binary star has a [[Bayer designation]] and is widely separated, it is possible that the members of the pair will be designated with superscripts; an example is [[Zeta Reticuli]], whose components are ζ<sup>1</sup> Reticuli and ζ<sup>2</sup> Reticuli.<ref>{{cite web | url = http://sunra.lbl.gov/~vhoette/Explorations/BinaryStars/ | title = Binary and Multiple Star Systems | publisher = Lawrence Hall of Science at the University of California | url-status = dead | archive-url = https://web.archive.org/web/20060207163102/http://sunra.lbl.gov/~vhoette/Explorations/BinaryStars/ | archive-date = 2006-02-07 }}</ref>

===Discoverer designations===
Double stars are also designated by an abbreviation giving the discoverer together with an index number.<ref>pp. 307–308, ''Observing and Measuring Double Stars'', Bob Argyle, ed., London: Springer, 2004, {{ISBN|1-85233-558-0}}.</ref> α Centauri, for example, was found to be double by Father Richaud in 1689, and so is designated ''RHD 1''.<ref name=aitken1 /><ref>Entry 14396-6050, discoverer code RHD 1AB,[http://ad.usno.navy.mil/wds/Webtextfiles/wdsnewframe3.html The Washington Double Star Catalog] {{Webarchive|url=https://archive.today/20120708194616/http://ad.usno.navy.mil/wds/Webtextfiles/wdsnewframe3.html |date=2012-07-08 }}, [[United States Naval Observatory]]. Accessed on line August 20, 2008.</ref> These discoverer codes can be found in the [[Washington Double Star Catalog]].<ref>[http://ad.usno.navy.mil/wds/Webtextfiles/wdsnewframe.html References and discoverer codes, The Washington Double Star Catalog] {{Webarchive|url=https://web.archive.org/web/20110517105248/http://ad.usno.navy.mil/wds/Webtextfiles/wdsnewframe.html |date=2011-05-17 }}, [[United States Naval Observatory]]. Accessed on line August 20, 2008.</ref>

===Hot and cold===
The secondary star in a binary star system may be designated as the ''hot companion'' or ''cool companion'', depending on its temperature relative to the primary star.

Examples:
* [[Antares]] (Alpha Scorpii) is a red supergiant star in a binary system with a hotter blue main-sequence star Antares B. Antares B can therefore be termed a hot companion of the cool supergiant.<ref>[http://simbad.u-strasbg.fr/simbad/sim-id?Ident=*%20alf%20Sco%20B] – see essential notes: "Hot companion to Antares at 2.9arcsec; estimated period: 678yr."</ref>
* [[Symbiotic star]]s, such as [[R Aquarii]], are binary star systems composed of a late-type giant star and a hotter companion object. Since the nature of the companion is not well-established in all cases, it may be termed a "hot companion".<ref>{{cite journal|title=The nature of symbiotic stars|author=Kenyon, S. J.|author2=Webbink, R. F.|date=1984|journal=Astrophysical Journal|volume=279|pages=252–283|doi=10.1086/161888|bibcode=1984ApJ...279..252K}}</ref>
* The [[luminous blue variable]] [[Eta Carinae]] has been determined to be a binary star system. The secondary appears to have a higher temperature than the primary and has therefore been described as being the "hot companion" star. It may be a [[Wolf–Rayet star]].<ref>{{cite journal|title=Detection of a Hot Binary Companion of η Carinae|author=Iping, Rosina C.|author2=Sonneborn, George|author3=Gull, Theodore R.|author4=Massa, Derck L.|author5=Hillier, D. John|journal=The Astrophysical Journal|volume=633|issue=1|pages=L37–L40|date=2005|doi=10.1086/498268|bibcode=2005ApJ...633L..37I|arxiv = astro-ph/0510581 |s2cid=119350572}}</ref>
* [[NASA]]'s [[Kepler mission]] has discovered examples of eclipsing binary stars where the secondary is the hotter component. [[KOI-74b]] is a 12,000&nbsp;K [[white dwarf]] companion of KOI-74 ({{KIC|6889235}}), a 9,400&nbsp;K early [[A-type main-sequence star]].<ref name="rowe">{{cite journal
| author=Rowe, Jason F.| author2=Borucki, William J.| author3=Koch, David| author4=Howell, Steve B.| author5=Basri, Gibor| author6=Batalha, Natalie| author7=Brown, Timothy M.| author8=Caldwell, Douglas| author9=Cochran, William D.| author10=Dunham, Edward| author11=Dupree, Andrea K.| author12=Fortney, Jonathan J.| author13=Gautier, Thomas N.| author14=Gilliland, Ronald L.| author15=Jenkins, Jon| author16=Latham, David W.| author17=Lissauer, Jack J.| author18=Marcy, Geoff| author19=Monet, David G.| author20=Sasselov, Dimitar| author21=Welsh, William F.
| title=Kepler Observations of Transiting Hot Compact Objects
| date=2010
| journal=The Astrophysical Journal Letters
| volume=713
| issue=2
| pages=L150–L154
| bibcode=2010ApJ...713L.150R
| doi=10.1088/2041-8205/713/2/L150
|arxiv = 1001.3420 | s2cid=118578253}}</ref><ref name="van_kerkwijk">{{cite journal
| author=van Kerkwijk, Marten H.| author2=Rappaport, Saul A.| author3=Breton, René P.| author4=Justham, Stephen| author5=Podsiadlowski, Philipp| author6=Han, Zhanwen
| title=Observations of Doppler Boosting in Kepler Light Curves
| date=2010
| journal=The Astrophysical Journal
| volume=715
| issue=1
| pages=51–58
| bibcode=2010ApJ...715...51V
| doi=10.1088/0004-637X/715/1/51
|arxiv = 1001.4539 | s2cid=15893663}}</ref><ref name="Borenstein">{{Cite web
| last = Borenstein | first = Seth
| title = Planet-hunting telescope unearths hot mysteries
| date = 4 January 2010 | type = 6:29 pm EST
| url = https://www.usnews.com/science/articles/2010/01/05/planet-hunting-telescope-unearths-hot-mysteries}}</ref> [[KOI-81b]] is a 13,000&nbsp;K white dwarf companion of KOI-81 ({{KIC|8823868}}), a 10,000&nbsp;K late [[B-type main-sequence star]].<ref name="rowe"/><ref name="van_kerkwijk"/><ref name="Borenstein"/>