Discovery of a 0.64 M ⊙ 13.4 au Companion to the roAp Star HIP 47145 = HR 3831 = IM Vel* *Based on observations collected at the European Southern Observatory, Chile, Program ID 110.241W.002.

Abstract

Our knowledge about the multiplicity of intermediate mass A- and B-type stars is still incomplete, in particular for high (3+) multiplicity systems. Here we report the discovery of a new companion to the nearby roAp star HIP 47145 = HR 3831 with a K band flux ratio of 4% based on a VLTI/GRAVITY interferometric observation. This new 0.64M ⊙ companion at a projected separation 187.5 mas ↔ 13.40 au explains the Hipparcos-GaiaDR2 proper motion change of HR 3831. Together with the previously known M ≈ 1M ⊙ companion at 3″ ↔ 214 au, this makes HR 3831 a hierarchical triple and a very likely progenitor for a system similar to 40 Eridani.