2026RNAAS..10...34W

Iota Aquarii is a nearby B-type star that has accrued a large amount of evidence for a close companion. Here we report on a VLTI/GRAVITY observation in which we detected a 1.2M_⊙ companion at a projected separation ρ = 7.1 mas ↔ 0.38 au. We conclude that this is the same companion that has been previously reported from direct spectral detection, but that its reported mass (1.00 ± 0.03M_⊙) had been somewhat underestimated. However, the Gaia-Hipparcos proper motion change and parallax discrepancy are not readily explained by the companion; if due to another hierarchical outer companion, it would have to be either a M ≲ 0.5M_⊙ red dwarf or a white dwarf to remain undetected.