Lucky Imaging of transiting planet host stars with LuckyCam

TL;DR

This study used Lucky Imaging with LuckyCam on the Nordic Optical Telescope to detect faint stellar companions around 16 transiting exoplanet host stars, confirming some known companions and discovering new candidates, which impact planet formation models.

Contribution

First high-resolution Lucky Imaging survey targeting transiting planet hosts, confirming known companions and identifying new candidate stellar companions.

Findings

Detected two new candidate stellar companions to TrES-1.

Confirmed stellar companions to CoRoT-2, CoRoT-3, TrES-2, TrES-4, and HAT-P-7.

Placed constraints on the spectral types and masses of potential companions.

Abstract

We obtained high-resolution, high-contrast optical imaging in the SDSS $i'$ band with the LuckyCam camera mounted on the 2.56m Nordic Optical Telescope, to search for faint stellar companions to 16 stars harbouring transiting exoplanets. The Lucky Imaging technique uses very short exposures to obtain near diffraction-limited images yielding sub-arcsecond sensitivity, allowing us to search for faint stellar companions within the seeing disc of the primary planet host. Here we report the detection of two candidate stellar companions to the planet host TrES-1 at separations $<6.5\arcsec$ and we confirm stellar companions to CoRoT-2, CoRoT-3, TrES-2, TrES-4, and HAT-P-7 already known in the literature. We do not confirm the candidate companions to HAT-P-8 found via Lucky Imaging by \citet{Bergfors2013}, however, most probably because HAT-P-8 was observed in poor seeing conditions. Our detection sensitivity limits allow us to place constraints on the spectral types and masses of the putative bound companions to the planet host stars in our sample. If bound, the stellar companions identified in this work would provide stringent observational constraints to models of planet formation and evolution. In addition these companions could affect the derived physical properties of the exoplanets in these systems.