Evans, D and Southworth, J and Smalley, B and JorgensenA, U and Dominik, M and Andersen, MI and Bozza, V and Bramich, DM and Burgdorf, MJ and Ciceri, S and D'Ago, G and Figuera Jaimes, R and Gu, S-H and Hinse, TC and Henning, TH and Hundertmark, M and Kains, N and Kerins, E and Korhonen, H and Kokotanekova, R and Kuffmeier, M and Longa-Peña, P and Mancini, L and MacKenzie, J and Popovas, A and Rabus, M and Rahvar, S and Sajadian, S and Snodgrass, C and Skottfelt, J and Surdej, J and Tronsgaard, R and Unda-Sanzana, E and von Essen, C and Wang, Y-B and Wertz, O (2017) High-resolution Imaging of Transiting Extrasolar Planetary systems (HITEP). II. Lucky Imaging results from 2015 and 2016. Astronomy and Astrophysics. ISSN 1432-0746

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Abstract

Context.
The formation and dynamical history of hot Jupiters is currently debated, with wide stellar binaries having been suggested as a potential formation pathway. Additionally, contaminating light from both binary companions and unassociated stars can significantly bias the results of planet characterisation studies, but can be corrected for if the properties of the contaminating star are known.
Aims.
We search for binary companions to known transiting exoplanet host stars, in order to determine the multiplicity properties of hot Jupiter host stars. We also search for and characterise unassociated stars along the line of sight, allowing photometric and spectroscopic observations of the planetary system to be corrected for contaminating light.
Methods.
We analyse lucky imaging observations of 97 Southern hemisphere exoplanet host stars, using the Two Colour Instrument on the Danish 1.54m telescope. For each detected companion star, we determine flux ratios relative to the planet host star in two passbands, and measure the relative position of the companion. The probability of each companion being physically associated was determined using our two-colour photometry.
Results
A catalogue of close companion stars is presented, including flux ratios, position measurements, and estimated companion star temperature. For companions that are potential binary companions, we review archival and catalogue data for further evidence. For WASP-77AB and WASP-85AB, we combine our data with historical measurements to determine the binary orbits, showing them to be moderately eccentric and inclined to the line of sight (and hence planetary orbital axis). Combining our survey with the similar Friends of Hot Jupiters survey, we conclude that known hot Jupiter host stars show a deficit of high mass stellar companions compared to the field star population; however, this may be a result of the biases in detection and target selection by ground-based surveys.

Item Type: Article
Additional Information: © EDP Sciences. This is the accepted author manuscript (AAM). The final published version (version of record) is available online via EDP Sciences at https://doi.org/10.1051/0004-6361/201731855 - please refer to any applicable terms of use of the publisher.
Uncontrolled Keywords: planets and satellites, dynamical evolution and stability, formation, techniques, high angular resolution, binaries, visual
Subjects: Q Science > QB Astronomy > QB460 Astrophysics
Divisions: Faculty of Natural Sciences > School of Chemical and Physical Sciences
Depositing User: Symplectic
Date Deposited: 21 Nov 2017 10:11
Last Modified: 21 Nov 2017 10:41
URI: http://eprints.keele.ac.uk/id/eprint/4248

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