Abstract
Ground-based direct imaging surveys like the Gemini Planet Imager Exoplanet Survey (GPIES) rely on Adaptive Optics (AO) systems to image and characterize exoplanets that are up to a million times fainter than their host stars. One factor that can reduce AO performance is turbulence induced by temperature differences in the instrument's immediate surroundings (e.g.: "dome seeing" or "mirror seeing"). In this analysis we use science observations, AO telemetry, and environmental data from September 2014 to February 2017 of the GPIES campaign to quantify the effects of "mirror seeing" on the performance of the GPI instrument. We show that GPI performance is optimal when the primary mirror (M1) is in equilibrium with the outside air temperature. We then examine the characteristics of mirror seeing by calculating the power spectral densities (PSD) of spatial and temporal Fourier modes. Inside the inertial range of the PSDs, we find that the spatial PSD amplitude increases when M1 is out of equilibrium and that the integrated turbulence may exhibit deviations from Kolmogorov atmospheric turbulence models and from the 1-layer frozen flow model. We conclude with an assessment of the current temperature control and ventilation strategy at Gemini South.
Highlights
Direct imaging is a technique used for the detection and characterization of gas giant exoplanets and their formation environments
We studied the effect of the temperature difference (ΔTM) between the primary mirror (M1) and the outside air, a proxy for mirror seeing, on the performance of the Gemini Planet Imager (GPI) at the Gemini South (GS)
Our analysis included 2977 60-s single exposures, 120 fully reduced observing sequences, and 582 adaptive optics (AO) telemetry sets recorded between September 2014 and February 2017 during the Gemini Planet Imager Exoplanet Survey (GPIES) campaign, as well as contemporaneous temperature and atmospheric seeing measurements
Summary
Direct imaging is a technique used for the detection and characterization of gas giant exoplanets and their formation environments. Each newly imaged planet helps constrain planet populations and provides a laboratory to study the formation, evolution, and atmospheric chemistry of massive, young, self-luminous planets, which are referred to as “young Jupiters.”[1,2,3,4,5,6,7] Known young Jupiters are ∼104 to 107 times fainter than their host stars in the near-infrared and are often separated by less than 0.5 arc sec. The Gemini Planet Imager (GPI) on the 8-m telescope at the Gemini South (GS) Observatory is one such instrument; it employs adaptive optics (AO) to correct for atmospheric turbulence and a coronagraph for starlight suppression.[3,8,9,10].
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