Atmospheric dynamics of Pegasi planets

TL;DR

This paper uses 3D simulations to explore atmospheric dynamics of close-orbiting Pegasi planets, revealing strong winds, temperature differences, and superrotation that influence observable properties like infrared flux and planetary evolution.

Contribution

It provides new insights into the atmospheric circulation patterns, temperature distributions, and observational signatures of Pegasi planets through detailed numerical simulations.

Findings

Winds of several km/sec are possible.

Day-night temperature differences reach 500-1000 K.

Infrared flux varies significantly over an orbital cycle.

Abstract

We present three-dimensional numerical simulations of the atmospheric dynamics of close-orbiting planets such as HD209458b. Our simulations show that winds of several km/sec and day-night temperature differences reaching 500-1000 K are possible at and above the photosphere. The circulation takes the form of a broad superrotating (eastward) equatorial jet. At 0.1-1 bar, the superrotation blows the hottest regions of the atmosphere downwind by 60 degrees of longitude, but at lower pressures the temperature pattern tracks the stellar illumination. We predict factors of several variation in the infrared flux received at Earth throughout an orbital cycle; if the photosphere is deep enough (>50-100 mbar pressure), the peak infrared emission should lead the time of secondary eclipse by 10 hours or more. Dynamics plays a key role in shaping the spectrum, clouds, chemistry, and long-term planetary evolution.