A lucky imaging multiplicity study of exoplanet host stars

TL;DR

This study uses lucky imaging to identify and confirm stellar companions around exoplanet host stars, revealing new companions and improving understanding of stellar multiplicity's role in planet formation.

Contribution

It presents new detections of stellar companions and confirms common proper motion, enhancing knowledge of stellar multiplicity among exoplanet hosts using lucky imaging.

Findings

Discovered a new low-mass stellar companion to HD185269.

Confirmed common proper motion of a companion to HD126614.

Provided detection limits for potential additional companions.

Abstract

To understand the influence of additional wide stellar companions on planet formation, it is necessary to determine the fraction of multiple stellar systems amongst the known extrasolar planet population. We target recently discovered radial velocity exoplanetary systems observable from the northern hemisphere and with sufficiently high proper motion to detect stellar companions via direct imaging. We utilize the Calar Alto 2.2m telescope in combination with its lucky imaging camera AstraLux. 71 planet host stars have been observed so far, yielding one new low-mass (0.239 \pm 0.022M\odot) stellar companion, 4.5 arcsec (227AU of projected separation) northeast of the planet host star HD185269, detected via astrometry with AstraLux. We also present follow-up astrometry on three previously discovered stellar companions, showing for the first time common proper motion of the 0.5 arcsec companion to HD126614. Additionally, we determined the achieved detection limits for all targets, which allows us to characterize the detection space of possible further companions of these stars.