The Astrophysical Journal (Jan 2025)

Limited Hysteresis in the Atmospheric Dynamics of Hot Jupiters

  • Thaddeus D. Komacek

DOI
https://doi.org/10.3847/1538-4357/adbae9
Journal volume & issue
Vol. 983, no. 1
p. 7

Abstract

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Over the past two decades, a coherent picture has emerged of the atmospheric dynamics of hot Jupiters from a combination of three-dimensional general circulation models and astronomical observations. This paradigm consists of hot Jupiters being spin-synchronized due to their close-in orbit, with a resulting large day-to-night irradiation gradient driving a day-to-night temperature contrast. This day-to-night temperature contrast in turn raises day-to-night pressure gradients that are balanced by a circulation with wind speeds on the order of km s ^−1 . The dominant feature of this circulation is a super-rotating equatorial jet, maintained by eddy-mean flow interactions that pump momentum into the jet. In this work, I explore the dependence of this circulation paradigm on the initial thermal and dynamical conditions in atmospheric circulation models of hot Jupiters. To do so, I conduct MITgcm simulations of the atmospheric circulation of hot Jupiters with both varying initial wind directions and initial temperature profiles. I find that the results are insensitive to the initial conditions, implying that the current paradigm of hot-Jupiter circulation exhibits at most limited hysteresis. I demonstrate that there is a single characteristic wind speed of hot Jupiters for given planetary and atmospheric parameters using an idealized scaling theory, and discuss implications for the interpretation of hot Jupiter observations.

Keywords