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Incoming links: Exoplanet atmospheric dynamics
Past exam of the mathematics course of the University of Cambridge 2018 iii Paper 315 4 a Solution Created 2026-10-03 Updated 2026-10-05
Three observational signatures constrain exoplanet atmospheric dynamics:
- A displaced maximum of the exoplanet thermal phase curve. If the thermal maximum precedes exoplanet secondary eclipse, the hottest region is displaced east of the substellar longitude in the usual synchronously rotating geometry. The observed offset for HD 189733 b is consistent with eastward heat advection and atmospheric superrotation; the early infrared phase-curve measurement established this effect.
- Warm nightside emission and a reduced day-night contrast. The amplitude of an exoplanet thermal phase curve constrains day-night heat redistribution. For HD 189733 b, the same observations found hemisphere brightness temperatures roughly and , supporting substantial transport to the nightside instead of purely local reradiation.
- Atmospheric line shifts after orbital motion is removed. A residual Doppler shift measures winds projected along the line of sight. A carbon monoxide signal blueshifted by roughly in HD 209458 b was interpreted as day-to-night winds in high-resolution transit spectroscopy. Rotational broadening and different limb velocities can supply additional dynamical information.
Opacity, exoplanet cloud distributions, and pressure-dependent brightness temperature affect the phase-curve interpretation. These measurements constrain circulation through atmospheric models; a single offset or line shift does not uniquely determine a three-dimensional wind field.
Past exam of the mathematics course of the University of Cambridge 2022 iii Paper 315 4 e Solution 2026-09-28
Exoplanet clouds and atmospheric haze add scattering and absorption opacity to an exoplanet transmission spectrum. A high opaque deck truncates the slant path and mutes molecular bands, while small aerosol particles can produce a blue scattering slope; patchiness creates mixtures of clear and cloudy limbs. In an exoplanet emission spectrum, aerosols move the photosphere to lower pressure, weaken or reshape molecular features, alter the geometric albedo, and can heat or cool layers depending on their shortwave and longwave absorption.
Observed aspects of exoplanet atmospheric dynamics include eastward equatorial atmospheric superrotation inferred from shifted thermal hot spots, day-night heat transport measured by phase-curve amplitude, and high-altitude winds measured from Doppler shifts of resolved spectral lines. Time-variable phase curves and eclipse maps also reveal changing cloud patterns and storms.