A dim candidate companion to \epsilon Cephei

TL;DR

Using advanced coronagraphy, we detected a faint companion near psilon Cephei, suggesting it is a late-type star at a very close angular separation, challenging previous dust explanations.

Contribution

First detection of a very close faint companion to psilon Cephei using a vector vortex coronagraph at an unprecedented small angle.

Findings

Detected a candidate companion at 330 mas separation.

The companion is likely a late-type K or early M star.

The near-infrared excess is not due to hot dust or IRAS source confusion.

Abstract

Using a vector vortex coronagraph behind the 1.5-m well-corrected subaperture (WCS) at Palomar, we detected a second object very close to \epsilon Cephei, a \delta Scuti F0 IV star. The candidate companion, ~50 times fainter than \epsilon Cephei, if physically associated, is a late-type K or early M star, and lies at an angular separation of 330 mas, or 1.1 \lambda/D for the WCS, making it the smallest angle detection ever realized with a coronagraph in terms of \lambda/D units. The projected separation of the putative companion is ~8.6 AU, most likely on a highly eccentric orbit. The recently detected near-infrared excess is thus likely not due to hot dust. Moreover, we also show that the previously reported IRAS 60 \mu m excess was due to source confusion on the galactic plane.