Editing Binary star (section)

===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"/>