View source for Coronium

{{Short description|Purported element in the Sun's corona later found to be 13-fold ionized iron}}
{{other uses|Coronium (disambiguation)}}
[[File:Solar eclipse 1999 4.jpg|right|thumb|A solar eclipse, with the solar corona visible.]]
'''Coronium''' was the name of a suggested [[chemical element]], hypothesised in the 19th century. The name, inspired by the [[solar corona]], was given by Gruenwald in 1887.<ref>{{cite journal |first=A. |last=Gruenwald |date=2 December 1887 |title=On remarkable relations between the spectrum of watery vapour and the line spectra of Hydrogen and Oxygen |journal=Chemical News |volume=LVI |issue=1462 |page=232 |via=Google Books |url=https://books.google.com/books?id=6ybOAAAAMAAJ&q=coronium&pg=PA232}}</ref> A new atomic thin green line in the solar corona was then considered to be emitted by a new element unlike anything else seen under laboratory conditions. It was later determined to be emitted by [[iron]] (Fe<sup>13+</sup>), so highly ionized that it was at that time impossible to produce in a laboratory.

== Solar spectroscopy ==
During the total [[solar eclipse of August 7, 1869|solar eclipse of 7&nbsp;August 1869]], a green [[emission line]] of wavelength 530.3&nbsp;nm was independently  observed by [[Charles Augustus Young]] (1834–1908) and [[William Harkness]] (1837–1903) in the [[solar corona|coronal]] [[Astronomical spectroscopy|spectrum]]. Since this  line did not correspond to that of any known material, it was proposed that it was due to an unknown element, provisionally named ''coronium''.

The supposed element was allegedly discovered also in the gases given off by [[Mount Vesuvius]] in 1898 by a team of Italian chemists led by {{ill|Raffaello Nasini|it|Raffaello Nasini}}.<ref>{{cite news |title=New Chemical Element |url=https://da.tj.news/viewer?opub=The_Daily_Gleaner&date=18981117&page=6&search=coronium&filename=0023_DG_A7202 |work=The Daily Gleaner |date=Nov 17, 1898 |page=6|url-access=subscription}}</ref> Nasini had no photographic record of the spectrum,<ref>{{cite journal|bibcode=1898Obs....21..325C |title=The problem of coronium |last1=Clerke |first1=A. M. |journal=The Observatory |date=1898 |volume=21 |page=325 }}</ref> and the observation was considered unconfirmed.<ref>{{cite journal|bibcode=1937JRASC..31..337C |title=Coronium |last1=Claridge |first1=George C. |journal=Journal of the Royal Astronomical Society of Canada |date=1937 |volume=31 |page=337 }}</ref>

In 1902, over thirty years after his famous predictions of new elements based on his periodic table, and shortly after the discovery of various [[noble gas|noble gases]], the Russian chemist [[Dmitri Mendeleev]] hypothesized that there existed two noble gases of atomic weight less than hydrogen.<ref>* ''Менделеев Д. И.'' [[s:ru:Попытка химического понимания мирового эфира (Д. И. Менделеев)|Попытка химического понимания мирового эфира]] (1902)</ref><ref>{{cite book|last = Mendeleyev|first = Dmitry Ivanovich|title = An Attempt Towards a Chemical Conception of the Ether | publisher = Longmans, Green, and Company | year = 1904}}</ref><ref>{{cite book |last=Ede |first=Andrew |title=The Chemical Element: A Historical Perspective |publisher=Greenwood Press |year=2006 |pages=83–84 |isbn=0-313-33304-1}}</ref><ref>{{cite journal |last=Lente |first=Gábor |title=Where Mendeleev was wrong: predicted elements that have never been found |journal=ChemTexts |year=2019 |volume=5|issue=3 |page=17 |doi=10.1007/s40828-019-0092-5 |bibcode=2019ChTxt...5...17L |url = https://link.springer.com/article/10.1007/s40828-019-0092-5|doi-access=free }}</ref>  The first, which he called "element x" or "newtonium", was his attempt at a chemical explanation of the [[luminiferous aether]].  He argued that it had an atomic weight of 0.14.  The second, which he called "element y" or coronium, was his attempt to explain the green emission lines from the Sun.  He argued that it had an atomic weight of 0.4.

It was not until the 1930s that [[Walter Grotrian]] and [[Bengt Edlén]] discovered that the spectral line at 530.3&nbsp;nm was due to [[highly charged ion|highly ionized]] [[iron]] (Fe<sup>13+</sup>); other unusual lines in the coronal spectrum were also caused by highly charged ions, such as [[nickel]], the high ionization being due to the extreme temperature of the [[solar corona]].<ref name=Morison>{{cite book |last=Morison |first=Ian |year=2008 |title=Introduction to Astronomy and Cosmology |page=61 |publisher=Wiley-Blackwell |isbn=978-0-470-03333-3 |url=https://books.google.com/books?id=yrV8vvJzgWkC&q=coronium+sun&pg=PA61}}</ref> The line at 530.3&nbsp;nm had previously been misclassified as iron line number&nbsp;1474.<ref name="Cosmos Portal">{{cite web |website=Cosmos Portal |title=Solar spectroscopy: Coronium |url=http://www.cosmosportal.org/articles/view/137561/ |accessdate=3 December 2011 |archive-url=https://web.archive.org/web/20111006125813/http://www.cosmosportal.org/articles/view/137561/ |archive-date=6 October 2011 |url-status=dead}}</ref>

==See also==
*[[Helium]]
*[[Nebulium]]
*[[Spectroscopy]]

==References==
{{reflist|25em}}

==Further reading==
* {{cite journal |last=Claridge |first=George C. |year=1937 |title=Coronium |journal=Journal of the Royal Astronomical Society of Canada |volume=31 |pages=337–346 |bibcode=1937JRASC..31..337C}}

==External links==
*{{cite web |title=History of Coronium |website=Laser Stars |url=http://laserstars.org/spectra/Coronium.html |access-date=2008-08-25}}

[[Category:Misidentified chemical elements]]
[[Category:Iron]]