Confirm whether Vy 2-2 hosts a post-common-envelope binary

Determine whether the planetary nebula Vy 2-2 hosts a post-common-envelope binary system, specifically whether its observed stellar emission lines originate from a main-sequence companion irradiated by the central star.

Background

The paper identifies stellar emission lines in Vy 2-2 that resemble those of a weak emission line star, but notes that such lines can instead arise from an irradiated main-sequence companion in a post-common-envelope binary system. Several independent characteristics—including the unusually high abundance discrepancy factor, concentric rings, bipolar morphology, collimated outflows, possible fluorine production, and broad Rayleigh–Raman-scattered H-alpha wings—are presented as evidence favoring a binary interpretation.

The binary nature remains observationally unconfirmed. The authors state that time-resolved spectroscopy of the stellar emission lines is needed to search for periodic radial-velocity variations and constrain the properties of a possible companion.

References

Therefore, the possibility is open that Vy 2-2 hosts a post-common envelope binary.

— Intermediate- and high-resolution optical spectroscopy on the nascent planetary nebula Vy 2-2: Evidence of binary-star evolution  (2610.21988 - Cala et al., 15 Oct 2026) in Section 4.2, “The formation of Vy 2-2 and its central star” (Sec. 4.2; label sec:binary)