Editing Stellar classification (section)

=== The old Harvard system (1897) ===
In 1897, another astronomer at Harvard, [[Antonia Maury]], placed the Orion subtype of Secchi class&nbsp;I ahead of the remainder of Secchi class&nbsp;I, thus placing the modern type&nbsp;B ahead of the modern type&nbsp;A. She was the first to do so, although she did not use lettered spectral types, but rather a series of twenty-two types numbered from I–XXII.<ref>Hearnshaw (1986) pp.&nbsp;111–112</ref><ref>{{cite journal |last1=Maury |first1=Antonia C. |last2=Pickering |first2=Edward C. |year=1897 |title=Spectra of bright stars photographed with the 11&nbsp;inch Draper Telescope as part of the Henry Draper Memorial |journal=Annals of Harvard College Observatory |volume=28 |pages=1 |bibcode=1897AnHar..28....1M}}</ref>
{| class="wikitable"
|+ Summary of 1897 Harvard system<ref name=spectroscopists/>
|-
! Groups !! Summary
|-
|align=center| I−V || included 'Orion type' stars that displayed an increasing strength in hydrogen absorption lines from group&nbsp;I to group&nbsp;V
|-
|align=center| VI || acted as an intermediate between the 'Orion type' and Secchi type&nbsp;I group
|-
|align=center| VII−XI || were Secchi's type&nbsp;1 stars, with decreasing strength in hydrogen absorption lines from groups&nbsp;VII−XI
|-
|align=center| XIII−XVI || included Secchi type&nbsp;2 stars with decreasing hydrogen absorption lines and increasing solar-type metallic lines
|-
|align=center| XVII−XX || included Secchi type&nbsp;3 stars with increasing spectral lines
|-
|align=center| XXI || included Secchi type&nbsp;4 stars
|-
|align=center| XXII || included Wolf–Rayet stars
|}

Because the 22&nbsp;Roman numeral groupings did not account for additional variations in spectra, three additional divisions were made to further specify differences: Lowercase letters were added to differentiate relative line appearance in spectra; the lines were defined as:<ref name=spectroscopists>{{cite web |title=Antonia Maury |website=www.projectcontinua.org |language=en-US |url=http://www.projectcontinua.org/antonia-maury/ |access-date=2020-06-10}}<br />
{{cite book |last=Hearnshaw |first=J.B. |date=17 March 2014 |title=The analysis of starlight: Two centuries of astronomical spectroscopy |edition=2nd |isbn=978-1-107-03174-6 |location=New York, NY |oclc=855909920 |url=https://www.worldcat.org/oclc/855909920}}<br />
{{cite book |last1=Gray |first1=Richard O. |last2=Corbally |first2=Christopher J. |last3=Burgasser |first3=Adam J. |title=Stellar spectral classification |year=2009 |publisher=Princeton University Press |isbn=978-0-691-12510-7 |location=Princeton, NJ |oclc=276340686 |url=https://www.worldcat.org/oclc/276340686}}</ref>
* (a): average width
* (b): hazy
* (c): sharp

Antonia Maury published her own stellar classification catalogue in 1897 called "Spectra of Bright Stars Photographed with the 11&nbsp;inch Draper Telescope as Part of the Henry Draper Memorial", which included 4,800&nbsp;photographs and Maury's analyses of 681&nbsp;bright northern stars. This was the first instance in which a woman was credited for an observatory publication.<ref>{{cite book |last1=Jones |first1=Bessie Zaban |last2=Boyd |first2=Lyle Gifford |year=1971 |title=The Harvard College Observatory: The first four directorships, 1839-1919 |edition=1st |place=Cambridge |publisher=M.A. Belknap Press of Harvard University Press |isbn=978-0-674-41880-6 |url=https://www.worldcat.org/oclc/1013948519 |oclc=1013948519}}</ref>