Editing Acrux (section)

==Nomenclature==

[[File:Deep Crux wide field with fog.jpg|thumb|left|The constellation [[Crux]]]]
''α Crucis'' (Latinised to ''Alpha Crucis'') is the system's [[Bayer designation]]; ''α<sup>1</sup>'' and ''α<sup>2</sup> Crucis'', those of its two main components stars. The designations of these two constituents as ''Acrux A'' and ''Acrux B'' and those of ''A's'' components—''Acrux Aa'' and ''Acrux Ab''—derive from the convention used by the [[Washington Multiplicity Catalog]] (WMC) for multiple star systems,{{dubious|date=April 2019}} and adopted by the [[International Astronomical Union]] (IAU).<ref name="planetnaming">{{cite arXiv |title=On the naming convention used for multiple star systems and extrasolar planets |date=2010 |eprint=1012.0707 |class=astro-ph.SR |last1= Hessman |first1=F. V. |last2= Dhillon |first2=V. S. |last3= Winget |first3=D. E. |last4= Schreiber |first4=M. R. |last5= Horne |first5=K. |last6= Marsh |first6=T. R. |last7= Guenther |first7=E. |last8= Schwope |first8=A. |last9= Heber |first9=U. }}</ref>{{Unreliable source?|date=April 2019|reason=This is only a proposal, but wasn't ratified. WDS is the adopted usage here.}}

The historical name ''Acrux'' for ''α<sup>1</sup> Crucis'' is an "[[American English|Americanism]]" coined in the 19th century, but entering common use only by the mid 20th century.<ref>''Memoirs of the Rev. Walter M. Lowrie: missionary to China'' (1849), p. 93. Described as an "Americanism" in ''The Geographical Journal'', vol. 92, Royal Geographical Society, 1938.</ref>{{Better source needed|date=April 2019|reason=Acrux was named by American Elijah H. Burritt in the 1850s}} In 2016, the [[International Astronomical Union]] organized a [[IAU Working Group on Star Names|Working Group on Star Names]] (WGSN)<ref name="WGSN">{{cite web | url=https://www.iau.org/science/scientific_bodies/working_groups/280/ | title=IAU Working Group on Star Names (WGSN)|access-date=22 May 2016}}</ref> to catalog and standardize proper names for stars. The WGSN states that in the case of [[Star system|multiple stars]] the name should be understood to be attributed to the brightest component by visual brightness.<ref name="WGSN2">{{cite web | url=http://www.pas.rochester.edu/~emamajek/WGSN/WGSN_bulletin2.pdf | title=Bulletin of the IAU Working Group on Star Names, No. 2 |access-date=12 October 2016}}</ref> The WGSN approved the name ''Acrux'' for the star ''Acrux Aa'' on 20 July 2016 and it is now so entered in the IAU Catalog of Star Names.<ref name="IAU-CSN"/>

Since Acrux is at −63° [[declination]], making it the southernmost first-magnitude star, it is only visible south of [[latitude]] 27° North. It barely rises from cities such as [[Miami]], [[United States]], or [[Karachi]], [[Pakistan]] (both around 25°N) and not at all from [[New Orleans]], [[United States]], or [[Cairo]], [[Egypt]] (both about 30°N). Because of Earth's [[axial precession]], the star was visible to ancient [[Hindu]] astronomers in [[India]] who named it ''Tri-shanku''. It was also visible to the [[ancient Romans]] and [[Ancient Greece|Greeks]], who regarded it as part of the constellation of [[Centaurus]].<ref>Richard Hinckley Allen, ''Star Names: Their Lore and Meaning,'' Dover Books, 1963.</ref>

In [[Chinese language|Chinese]], {{lang|zh|十字架}} ({{lang|zh-Latn|Shí Zì Jià}}, "[[Chinese constellations#The Southern Asterisms (近南極星區)|Cross]]"), refers to an asterism consisting of Acrux, [[Mimosa (star)|Mimosa]], [[Gamma Crucis]] and [[Delta Crucis]].<ref>{{in lang|zh}} ''中國星座神話'', written by 陳久金. Published by 台灣書房出版有限公司, 2005, {{ISBN|978-986-7332-25-7}}.</ref> Consequently, Acrux itself is known as {{lang|zh|十字架二}} ({{lang|zh-Latn|Shí Zì Jià èr}}, "the Second Star of Cross").<ref>{{in lang|zh}} [http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_a_al.htm 香港太空館 - 研究資源 - 亮星中英對照表] {{webarchive|url=https://web.archive.org/web/20100903162121/http://www.lcsd.gov.hk/CE/Museum/Space/Research/StarName/c_research_chinengstars_a_al.htm |date=2010-09-03 }}, Hong Kong Space Museum. Accessed on line November 23, 2010.</ref>

This star is known as ''Estrela de Magalhães'' ("Star of [[Magellan]]") in [[Portuguese language|Portuguese]].<ref>{{cite journal|doi=10.1590/S1806-11172008000100007 |title=Transformação de coordenadas aplicada à construção da maquete tridimensional de uma constelação |journal=Revista Brasileira de Ensino de Física |volume=30 |pages=1306.1–1306.7 |year=2008 |last1=Silva |first1=Guilherme Marques dos Santos |last2=Ribas |first2=Felipe Braga |last3=Freitas |first3=Mário Sérgio Teixeira de |doi-access=free }}</ref>