Hidden Companions to Intermediate-mass Stars. XIII. Discovery of a 0.80 M ⊙, 4.3 au Companion to HIP 7298*

Abstract

Abstract Proper motion changes between astrometric surveys provide a hint for unresolved companions and near-infrared interferometry is arguably the most efficient way to reveal or constrain their nature. Here we report on the VLTI/GRAVITY. detection of a companion to the nearby star HIP 7298 with a K band flux ratio of 11.9% at a projected separation ρ = 57.1 mas ↔ 4.3 au. Through isochrone fitting we find that the primary is a 1 Gyr old M A  = 1.56M ⊙ star while the newly discovered secondary is a M B  = 0.80M ⊙ K dwarf. The stars will most likely avoid common envelope evolution and will become a system similar to Gliese 86 in about 1.5 Gyr.