Secondary eclipse observations for seven hot-Jupiters from the Anglo-Australian Telescope

Abstract

We report detections and constraints for the near infrared Ks band secondary eclipses of seven hot-Jupiters using the IRIS2 infrared camera on the Anglo-Australian Telescope. Eclipses in the Ks band for WASP-18b and WASP-36b have been measured for the first time. We also present new measurements for the eclipses of WASP-4b, WASP-5b, and WASP-46b, as well as upper limits for the eclipse depths of WASP-2b and WASP-76b. In particular, two full eclipses of WASP-46b were observed, allowing us to demonstrate the repeatability of our observations via independent analyses on each eclipse. Significant numbers of eclipse depths for hot-Jupiters have now been measured in both Ks and the four Spitzer IRAC bandpasses. We discuss these measurements in the context of the broadband colours and brightness temperatures of the hot-Jupiter atmosphere distribution. Specifically, we re-examine the proposed temperature dichotomy between the most irradiated, and mildly irradiated planets. We find no evidence for multiple clusters in the brightness temperature equilibrium temperature distributions in any of these bandpasses, suggesting a continuous distribution of heat re-emission and circulation characteristics for these planets.

Examining Tatooine: Atmospheric Models of Neptune-Like Circumbinary Planets

“…For Kepler 47b, the maximum temperature variations between different points in orbit are of order a few Kelvin as predicted by the GCM. This is quite far out of the reach of current ground based efforts, which have errors of 100s of Kelvin (Zhou et al 2015;von Essen et al 2015). Recent best efforts to measure thermal emission from an exoplanet using Spitzer phase curves have achieved errors of only 20-60K (Knutson et al 2009(Knutson et al , 2012Maxted et al 2013;Wong et al 2015;Zellem et al 2014), but this would still not be small enough to measure the extremely small temperature differences of a circumbinary planet with any certainty.…”

WASP-4b Arrived Early for the TESS Mission

“…Zhou et al (2015) fixed the epoch, and let e cos ω float. Using the reported dates of observation, we converted their e cos ω values into an occultation time using Equation 1 of the text.…”

Estimating dayside effective temperatures of hot Jupiters and associated uncertainties through Gaussian process regression

“…In reality, secondary eclipse depth is not known at all wavelengths. At best, a planet may have broad-band photometry from the Infrared Array Camera (IRAC; Fazio et al 2004) on Spitzer (Werner et al 2004;e.g., Deming et al 2007;Nymeyer et al 2011;Todorov et al 2014;Kammer et al 2015;Wong et al 2015) and some near-IR observations from ground-based telescopes (e.g., Zhao et al 2012;Croll et al 2015;Zhou et al 2015;Martioli et al 2018), as well as 1.1-1.7 µm spectral data from the Wide Field Camera 3 (WFC3; Cheng et al 2000) on the Hubble Space Telescope (Bahcall 1986;e.g., Crouzet et al 2014;Ranjan et al 2014;Line et al 2016;Cartier et al 2017;Mansfield et al 2018). More realistically, most planets are observed in only a small subset of these bands.…”

“…As Croll et al (2015) discuss, uncertainties claimed for these measurements have historically been unreliable due to the systematics involved with near-IR, ground-based photometry and a lack of demonstrated repeatability. While Croll et al (2015) and Zhou et al (2015) show that uncertainties for ground-based eclipse measurements can be robustly estimated through careful systematic analysis and multiple independent measurements, there is not yet a critical mass of such repeated measurements in the literature. While we neglect ground-based observations in this analysis, our GP regression method can trivially be extended to an arbitrary number of observations in any ensemble of bands.…”