On the Presence of Water and Global Circulation in the Transiting Planet HD 189733b

TL;DR

This study models the atmosphere of exoplanet HD 189733b, confirming water presence, non-isothermal conditions, and constraining CO levels, while estimating energy redistribution efficiency based on infrared observations.

Contribution

It provides the first detailed atmospheric model comparison with infrared data for HD 189733b, constraining water and CO presence and estimating energy redistribution.

Findings

Water is present in the atmosphere.

The day side has a non-isothermal structure.

Energy redistribution efficiency is approximately 43%.

Abstract

Detailed models are compared to recent infrared observations of the nearby extrasolar planet, HD 189733b. It is demonstrated that atmospheric water is present and that the planet's day side has a non-isothermal structure down to gas pressures of ~ 0.1 bars. Furthermore, model spectra with different amounts of CO are compared to the observations and an atmosphere absent of CO is excluded at roughly 2-sigma. Constraining the CO concentration beyond that is unfortunately not possible with the current Spitzer photometry. However, radically enhanced (or depleted) metal abundances are unlikely and the basic composition of this planet is probably similar to that of its host star. When combined with Spitzer observations, a recent ground-based upper limit for the K-band day side flux allows one to estimate the day-to-night energy redistribution efficiency to be ~ 43%.