Editing Eta Carinae (section)

===Great Eruption===
[[File:Historical visual lightcurve for Eta Carinae (1686 - 2014).png|upright=1.4|thumb|left|alt=Historical visual lightcurve for η&nbsp;Carinae from 1686 to 2015|The lightcurve of η&nbsp;Carinae from some of the earliest observations to the current day]]
In 1827, Burchell specifically noted η&nbsp;Carinae's unusual brightness at 1st&nbsp;magnitude, and was the first to suspect that it varied in brightness.<ref name="frew"/> [[John Herschel]], who was in South Africa at the time, made a detailed series of accurate measurements in the 1830s showing that η&nbsp;Carinae consistently shone around magnitude&nbsp;1.4 until November 1837. On the evening of 16 December 1837, Herschel was astonished to see that it had brightened to slightly outshine [[Rigel]].<ref name="herschel"/> This event marked the beginning of a roughly 18-year period known as the Great Eruption.<ref name="frew"/>

η&nbsp;Carinae was brighter still on 27&nbsp;January 1838, equivalent to [[Alpha Centauri]], before fading slightly over the following three months. Herschel did not observe the star after this, but received correspondence from the Reverend W.S. Mackay in Calcutta, who wrote in 1843, "To my great surprise I observed this March last (1843), that the star η&nbsp;Argus had become a star of the first magnitude fully as bright as [[Canopus]], and in colour and size very like [[Arcturus]]." Observations at the [[Cape of Good Hope]] indicated it peaked in brightness, surpassing Canopus, from 11 to 14 March 1843, then began to fade, then brightened to between the brightness of Alpha Centauri and Canopus between 24 and 28 March before fading once again.<ref name="herschel">{{cite book |last=Herschel |first=John Frederick William |author-link=John Herschel |title=Results of astronomical observations made during the years 1834, 5, 6, 7, 8, at the Cape of Good Hope: being the completion of a telescopic survey of the whole surface of the visible heavens, commenced in 1825 |url=https://books.google.com/books?id=8WBNAAAAcAAJ&q=Canopus |publisher=[[Smith, Elder and Co.]] |location=London |volume=1 |year=1847 |pages=33–35 |bibcode=1847raom.book.....H}}</ref> For much of 1844 the brightness was midway between [[Alpha Centauri]] and [[Beta Centauri]], around magnitude +0.2, before brightening again at the end of the year. At its brightest in 1843 it likely reached an apparent magnitude of −0.8, then −1.0 in 1845.<ref name="smithfrew">{{cite journal |last1=Smith |first1=Nathan |last2=Frew |first2=David J. |title=A revised historical light curve of η&nbsp;Carinae and the timing of close periastron encounters |journal=Monthly Notices of the Royal Astronomical Society |volume=415 |issue=3 |pages=2009–2019 |year=2011 |arxiv=1010.3719 |s2cid=118614725 |bibcode=2011MNRAS.415.2009S |doi=10.1111/j.1365-2966.2011.18993.x|doi-access=free }}</ref> The peaks in 1827, 1838 and 1843 are likely to have occurred at the [[periastron]] passage—the point the two stars are closest together—of the [[Binary star|binary]] orbit.<ref name="damineli">{{cite journal |last=Damineli |first=A. |title=The 5.52&nbsp;year cycle of Eta Carinae |journal=[[Astrophysical Journal Letters]] |volume=460 |pages=L49 |year=1996 |bibcode=1996ApJ...460L..49D |doi=10.1086/309961 |doi-access=free }}</ref> From 1845 to 1856, the brightness decreased by around 0.1&nbsp;magnitudes per year, but with possible rapid and large fluctuations.<ref name="smithfrew"/>

In their oral traditions, the Boorong clan of the [[Wergaia]] people of [[Lake Tyrrell]], north-western Victoria, Australia, told of a reddish star they knew as ''Collowgullouric War''<!-- In Table 3, Hamacher & Frew spell it "Collowgulloric War", without the 2nd 'u', and the same a few lines down with "Collowgulloric Warepil". However, the Wotjobaluk form is given as "Collow-collouric", and in the photocopy of Stanbridge (1858:140) in sect. 4, it's clearly "Collowgullouric War". The translation is "female crow",, only the identification is "wife of War". --> {{IPAc-en|'|k|Q|l|@|g|V|l|@|r|ɪ|k|_|'|w|ɑr}} "Old Woman Crow", the wife of ''War'' "Crow" ([[Canopus]]).<ref name="GSSCZ">Or more accurately ''gala-gala gurrk waa'', with the onset of ''gurrk'' "woman" lost in Stanbridge. {{cite book |last=Reid |first=Julie |year=2008 |title=Wergaia Community Grammar and Dictionary |url=https://books.google.com/books?id=haxkygAACAAJ |via=Google }}</ref> In 2010, astronomers Duane Hamacher and David Frew from [[Macquarie University]] in Sydney showed that this was η&nbsp;Carinae during its Great Eruption in the 1840s.<ref name=boorong>{{cite journal |last1=Hamacher |first1=Duane W. |last2=Frew |first2=David J. |year=2010 |title=An aboriginal Australian record of the great eruption of Eta Carinae |journal=Journal of Astronomical History and Heritage |volume=13 |issue=3 |pages=220–234 |arxiv=1010.4610 |bibcode=2010JAHH...13..220H |s2cid=118454721 |doi=10.3724/SP.J.1440-2807.2010.03.06}}</ref> From 1857, the brightness decreased rapidly until it faded below [[naked-eye]] visibility by 1886. This has been calculated to be due to the condensation of [[Cosmic dust|dust]] in the ejected material surrounding the star, rather than to an intrinsic change in luminosity.<ref name="davidson1997">{{cite journal |last1=Davidson |first1=Kris |last2=Humphreys |first2=Roberta M. |author2-link=Roberta M. Humphreys |title=Eta Carinae and its environment |journal=[[Annual Review of Astronomy and Astrophysics]] |volume=35 |pages=1–32 |year=1997 |bibcode=1997ARA&A..35....1D |s2cid=122193829 |doi=10.1146/annurev.astro.35.1.1}}</ref>