Editing Stellar classification (section)

===Spectral peculiarities===
Additional nomenclature, in the form of lower-case letters, can follow the spectral type to indicate peculiar features of the spectrum.<ref>{{cite web |url=http://www.skyandtelescope.com/astronomy-equipment/the-spectral-types-of-stars/?showAll=y |title=The Spectral Types of Stars |work=Sky & Telescope |first=Alan |last=MacRobert |date=1 August 2006}}</ref>

{| class="wikitable"
|-
! Code
! Spectral peculiarities for stars
|-
! :
| uncertain spectral value<ref name="CDS"/>
|-
! ...
| Undescribed spectral peculiarities exist
|-
! !
| Special peculiarity
|-
! comp
| Composite spectrum<ref name="Allen">{{cite web |last1=Allen |first1=J. S. |title=The Classification of Stellar Spectra |website=[[University College London|UCL]] Department of Physics and Astronomy: Astrophysics Group |url=http://www.star.ucl.ac.uk/~pac/spectral_classification.html |access-date=1 January 2014}}</ref>
|-
! e
| Emission lines present<ref name="Allen"/>
|-
! [e]
| [[Forbidden mechanism|"Forbidden" emission lines]] present
|-
! er
| "Reversed" center of emission lines weaker than edges
|-
! eq
| Emission lines with [[P Cygni profile]]
|-
! f
| N&nbsp;III and He&nbsp;II emission<ref name="CDS"/>
|-
! f*
| [[nitrogen|N]]&nbsp;IV 4058Å is stronger than the [[Nitrogen|N]]&nbsp;III 4634Å, 4640Å, & 4642Å lines<ref name="JMA">{{cite journal |bibcode=2007ApJ...660.1480M |arxiv=astro-ph/0612012 |title=Pismis 24-1: The Stellar Upper Mass Limit Preserved |journal=The Astrophysical Journal |volume=660 |issue=2 |pages=1480–1485 |last1=Maíz Apellániz |first1=J. |last2=Walborn |first2=Nolan R. |last3=Morrell |first3=N. I. |last4=Niemela |first4=V. S. |last5=Nelan |first5=E. P. |year=2007 |doi=10.1086/513098|s2cid=15936535 }}</ref>
|-
! f+
| Si&nbsp;IV 4089Å & 4116Å are emitted, in addition to the N&nbsp;III line<ref name="JMA"/>
|-
! f?
| C&nbsp;III 4647–4650–4652Å emission lines with comparable strength to the N&nbsp;III line<ref name=walborn2010>{{cite journal|bibcode=2010ApJ...711L.143W|title=Early Results from the Galactic O-Star Spectroscopic Survey: C III Emission Lines in of Spectra|journal=The Astrophysical Journal Letters|volume=711|issue=2|pages=L143|last1=Walborn|first1=Nolan R.|last2=Sota|first2=Alfredo|last3=Maíz Apellániz|first3=Jesús|last4=Alfaro|first4=Emilio J.|last5=Morrell|first5=Nidia I.|last6=Barbá|first6=Rodolfo H.|last7=Arias|first7=Julia I.|last8=Gamen|first8=Roberto C.|year=2010|doi=10.1088/2041-8205/711/2/L143|arxiv = 1002.3293 |s2cid=119122481}}</ref>
|-
! (f)
| N&nbsp;III emission, absence or weak absorption of He&nbsp;II
|-
! (f+)
|<ref name="Cecilia">{{cite journal |bibcode=2009AJ....138..510F |arxiv=0907.1033 |title=Spectroscopic Study of the N159/N160 Complex in the Large Magellanic Cloud |journal=The Astronomical Journal |volume=138 |issue=2 |pages=510–516 |last1=Fariña |first1=Cecilia |last2=Bosch |first2=Guillermo L. |last3=Morrell |first3=Nidia I. |last4=Barbá |first4=Rodolfo H. |last5=Walborn |first5=Nolan R. |year=2009 |doi=10.1088/0004-6256/138/2/510|s2cid=18844754 }}</ref>
|-
! ((f))
| Displays strong He II absorption accompanied by weak N III emissions<ref name="GRauw">{{cite journal |bibcode=2007A&A...463..981R |arxiv=astro-ph/0612622 |title=Early-type stars in the core of the young open cluster Westerlund 2 |journal=Astronomy and Astrophysics |volume=463 |issue=3 |pages=981–991 |last1=Rauw |first1=G. |last2=Manfroid |first2=J. |last3=Gosset |first3=E. |last4=Nazé |first4=Y. |last5=Sana |first5=H. |last6=De Becker |first6=M. |last7=Foellmi |first7=C. |last8=Moffat |first8=A. F. J. |year=2007 |doi=10.1051/0004-6361:20066495|s2cid=17776145 }}</ref>
|-
! ((f*))
|<ref name=Cecilia/>
|-
! h
| WR stars with hydrogen emission lines.<ref name=WR/>
|-
! ha
| WR stars with hydrogen seen in both absorption and emission.<ref name=WR/>
|-
! He wk
| Weak Helium lines
|-
! k
| Spectra with interstellar absorption features
|-
! m
| Enhanced metal features<ref name="Allen"/>
|-
! n
| Broad ("nebulous") absorption due to spinning<ref name="Allen"/>
|-
! nn
| Very broad absorption features<ref name="CDS"/>
|-
! neb
| A nebula's spectrum mixed in<ref name="Allen"/>
|-
! p
| Unspecified peculiarity, [[peculiar star]].<ref group=lower-alpha>When [[Ap and Bp stars|used with A-type stars]], this instead refers to abnormally strong metallic spectral lines</ref><ref name="Allen"/>
|-
! pq
| Peculiar spectrum, similar to the spectra of novae
|-
! q
| [[P Cygni profile]]s
|-
! s
| Narrow ("sharp") absorption lines<ref name="Allen"/>
|-
! ss
| Very narrow lines
|-
! sh
| [[Shell star]] features<ref name="Allen"/>
|-
! var
| Variable spectral feature<ref name="Allen"/> (sometimes abbreviated to "v")
|-
! wl
| Weak lines<ref name="Allen"/> (also "w" & "wk")
|-
! Element<br />symbol
| Abnormally strong spectral lines of the specified element(s)<ref name="Allen"/>
|-
! z
| indicating an abnormally strong ionised helium line at {{val|468.6|ul=nm}}<ref name=arias/>
|}

For example, [[59 Cygni]] is listed as spectral type&nbsp;B1.5Vnne,<ref name="Lesh">{{Cite journal |doi=10.1086/190179 |title=The Kinematics of the Gould Belt: An Expanding Group? |journal=The Astrophysical Journal Supplement Series |volume=17 |pages=371 |year=1968 |last1=Rountree Lesh |first1=J. |bibcode=1968ApJS...17..371L|doi-access=free }}</ref> indicating a spectrum with the general classification B1.5V, as well as very broad absorption lines and certain emission lines.