A Lucky Imaging search for stellar sources near 74 transit hosts

TL;DR

This study used Lucky Imaging to identify close stellar sources near 74 transiting planet hosts, revealing new companions that could impact planetary parameter estimates and system evolution understanding.

Contribution

It extends high-resolution Lucky Imaging surveys to 74 transiting planet hosts, discovering new stellar companions and providing their separations and flux ratios.

Findings

New stellar sources found within 1 arcsec of five hosts.

Additional companions identified between 1 and 4 arcsec for two hosts.

Enhanced understanding of stellar multiplicity around transiting planet hosts.

Abstract

Many transiting planet host stars lack high resolution imaging and thus close stellar sources can be missed. Those unknown stars potentially bias the derivation of the planetary and stellar parameters from the transit light curve, no matter if they are bound or not. In addition, bound stellar companions interact gravitationally with the exoplanet host star, the disk and the planets and can thus influence the formation and evolution of the planetary system strongly. We extended our high-resolution Lucky Imaging survey for close stellar sources by 74 transiting planet host stars. 39 of these stars lack previous high-resolution imaging, 23 are follow up observations of companions or companion candidates, and the remaining stars have been observed by others with AO imaging though in different bands. We determine the separation of all new and known companion candidates and estimate the flux ratio in the observed bands. All observations were carried out with the Lucky Imaging camera AstraLux Norte at the Calar Alto 2.2 m telescope in i' and z' passbands. We find new stellar sources within 1 arcsec to HAT-P-27, HAT-P-28, HAT-P-35, WASP-76, and WASP-103, and between 1 and 4 arcsec to HAT-P-29 and WASP-56.