Editing Stellar classification (section)

===Spectral types of non-single objects: Classes P and Q===
Finally, the classes '''P''' and '''Q''' are left over from the system developed by [[Annie Jump Cannon|Cannon]] for the ''[[Henry Draper Catalogue]]''. They are occasionally used for certain objects, not associated with a single star: Type&nbsp;P objects are stars within [[planetary nebula]]e (typically young white dwarfs or hydrogen-poor M giants); type&nbsp;Q objects are [[nova]]e.{{citation needed|date=April 2019}}