Editing Stellar classification (section)

====Class C====
{{Main|Carbon star}}
[[File:Curious spiral spotted by ALMA around red giant star R Sculptoris (data visualisation).jpg|thumb|Image of the carbon star [[R Sculptoris]] and its striking spiral structure]]
Originally classified as R and N&nbsp;stars, these are also known as ''carbon stars''. These are red giants, near the end of their lives, in which there is an excess of carbon in the atmosphere. The old R and N classes ran parallel to the normal classification system from roughly mid-G to late M. These have more recently been remapped into a unified carbon classifier C with N0 starting at roughly C6. Another subset of cool carbon stars are the C–J-type stars, which are characterized by the strong presence of molecules of [[Carbon-13|<sup>13</sup>]] [[cyanide|CN]] in addition to those of [[Carbon-12|<sup>12</sup>]] [[cyanide|CN]].<ref>Bouigue, R. (1954). Annales d'Astrophysique, Vol.&nbsp;17, p.&nbsp;104</ref> A few main-sequence carbon stars are known, but the overwhelming majority of known carbon stars are giants or supergiants. There are several subclasses:
* C-R – Formerly its own class (''R'') representing the carbon star equivalent of late G- to early K-type stars.
* C-N – Formerly its own class representing the carbon star equivalent of late K- to M-type stars.
* C-J – A subtype of cool C stars with a high content of [[Carbon-13|<sup>13</sup>C]].
* C-H – [[Population II]] analogues of the C-R stars.
* C-Hd – Hydrogen-deficient carbon stars, similar to late G supergiants with [[Methylidyne radical|CH]] and [[diatomic carbon|C<sub>2</sub>]] bands added.