Editing Stellar classification (section)

===Class K===
{{See also|K-type main-sequence star}}
{{Redirect|K-type star|the Korean nuclear fusion project|KSTAR}}
[[File:K5V star spectrum.png|thumb|Spectrum of a hypothetical K5V star]]
K-type stars are orangish stars that are slightly cooler than the Sun. They make up about 12% of the main-sequence stars in the solar neighborhood.<ref group=lower-alpha name="proportions"/><ref name="LeDrew2001"/> There are also giant K-type stars, which range from [[hypergiant]]s like [[RW Cephei]], to [[Giant star|giants]] and [[supergiant]]s, such as [[Arcturus]], whereas [[K-type main-sequence star|orange dwarfs]], like [[Alpha Centauri]]&nbsp;B, are main-sequence stars.

They have extremely weak hydrogen lines, if those are present at all, and mostly neutral metals ([[manganese|Mn]]&nbsp;I, [[iron|Fe]]&nbsp;I, [[silicon|Si]]&nbsp;I). By late K, molecular bands of [[titanium monoxide|titanium oxide]] become present. Mainstream theories (those rooted in lower harmful radioactivity and star longevity) would thus suggest such stars have the optimal chances of heavily evolved life developing on orbiting planets (if such life is directly analogous to Earth's) due to a broad habitable zone yet much lower harmful periods of emission compared to those with the broadest such zones.<ref>{{cite web |url=http://spacefellowship.com/2009/08/10/on-a-cosmological-timescale-the-earths-period-of-habitability-is-nearly-over/ |title=On a cosmological timescale, The Earth's period of habitability is nearly over &#124; International Space Fellowship |publisher=Spacefellowship.com |access-date=22 May 2012}}</ref><ref>{{cite web |url=https://www.nasa.gov/feature/goddard/2019/k-star-advantage |title="Goldilocks" Stars May Be "Just Right" for Finding Habitable Worlds |publisher=NASA.com |date=7 March 2019 |access-date=26 August 2021 }}</ref>

'''Example spectral standards:'''<ref name="Garrison"/>
* K0V – [[Sigma Draconis]]
* K0III – [[Pollux (star)|Pollux]]
* K0III – [[Epsilon Cygni]]
* K2V – [[Epsilon Eridani]]
* K2III – [[Kappa Ophiuchi]]
* K3III – [[Rho Boötis]]
* K5V – [[61 Cygni|61 Cygni A]]
* K5III – [[Gamma Draconis]]