Hidden Companions to Intermediate-mass Stars. XVIII. Discovery of a 0.88M ⊙, 26 au Companion to n Centauri* *Based on observations collected at the European Southern Observatory, Chile, Program ID 111.24UP.001.

Abstract

n Centauri is a nearby A-type star. Here we report the discovery of a companion with an H band flux ratio fBfA=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 = 2.07M ⊙ and M B = 0.88M ⊙ and an age of 900 Myr. The newly discovered companion explains the Δv = 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 ≳ 0.52M ⊙ for a main sequence star) within ρ > 5 mas ↔ 0.23 au.