Page "Extrasolar planet" Paragraph 52

Hessman et al.

state that the implicit system for exoplanet names utterly failed with the discovery of circumbinary planets.

They note that the discoverers of the two planets around HW Virginis tried to circumvent the naming problem by calling them " HW Vir 3 " and " HW Vir 4 ", i. e. the latter is the 4th object – stellar or planetary – discovered in the system.

They also note that the discoverers of the two planets around NN Serpentis were confronted with multiple suggestions from various official sources and finally chose to use the designations " NN Ser c " and " NN Ser d ."