Hidden Companions to Intermediate-mass Stars. XVIII. Discovery of a 0.88M ⊙, 26 au Companion to n Centauri*

Abstract n Centauri is a nearby A-type star. Here we report the discovery of a companion with an H band flux ratio <?CDATA f_Bf_A=3.9 % ± 0.4 %?> f B f A = 3.9 % ± 0.4 % at a projected separation ρ = 570 mas ↔ 26 au based on the acquisition camera image of a VLTI/GRAVITY observation. Isochrone fitting yields masses M A = 2.07 M ⊙ and M B = 0.88 M ⊙ and an age of 900 Myr. The newly discovered companion explains the Δ v = 2.3 ± 0.1 km s −1 Gaia-Hipparcos proper motion change of n Cen in both direction and magnitude as well as its X-ray emission. The interferometric data excludes the presence of any additional companion to the primary with a K band flux ratio higher than 0.9% ( M ≳ 0.52 M ⊙ for a main sequence star) within ρ > 5 mas ↔ 0.23 au.