It seems that whenever someone has trouble viewing one or more of the components of a double star the possibility of the "Missing" component being variable is posited. In all the cases that I can recall the missing component either had a incorrect visual magnitude listed or the listed magnitude was in the infrared range leading to the misinterpretation as to its ease of visibility.
I know of a couple of doubles where the primary is an algol type eclipsing variable but is anyone aware of a double star where a secondary component exhibits a significant change in magnitude - half a magnitude or more? True binaries preferred.
Edited by ssmith, 17 January 2020 - 11:33 AM.