Evolutionary relationship between planetary-nebula rings and GR Cygni’s ionized rings

Determine whether the rings observed in planetary nebulae are evolutionarily related to the widely separated concentric ionized rings surrounding the symbiotic binary GR Cygni.

Background

The paper compares the widely spaced pair of ionized rings around GR Cygni with ring and arc structures observed in true planetary nebulae. Although rings occur in both environments, the authors note that planetary-nebula rings are generally arranged as tightly spaced series and therefore appear morphologically distinct from the rings surrounding GR Cygni. The evolutionary connection between these structures is consequently left unresolved.

References

Thus it is unclear whether these rings in PNe are evolutionarily related to those surrounding GR Cyg.

— Ionized Nebulae Around Two New Symbiotic Stars: GR Cygni and [D75] 141  (2609.04036 - Bond et al., 3 Sep 2026) in Section 8.1, “GR Cyg / StDr Objet 14”