Hot Jupiters: Origins, Structure, Atmospheres

• Published in: Journal of geophysical research. Planets Vol. 126; no. 3
• Main Authors: Fortney, Jonathan J., Dawson, Rebekah I., Komacek, Thaddeus D.
• Format: Journal Article
• Language: English
• Published: 01.03.2021
• ISSN: 2169-9097; 2169-9100
• DOI: 10.1029/2020JE006629

We provide a brief review of many aspects of the planetary physics of hot Jupiters. Our aim is to cover most of the major areas of current study while providing the reader with additional references for more detailed follow‐up. We first discuss giant planet formation and subsequent orbital evolution via disk‐driven torques or dynamical interactions. More than one formation pathway is needed to understand the population. Next, we examine our current understanding of the evolutionary history and current interior structure of the planets, where we focus on bulk composition as well as viable models to explain the inflated radii of the population. Finally, we discuss aspects of their atmospheres in the context of observations and 1D and 3D models, including atmospheric structure and escape, spectroscopic signatures, and complex atmospheric circulation. The major opacity sources in these atmospheres, including alkali metals, water vapor, and others, are discussed. We discuss physics that control the 3D atmospheric circulation and day‐to‐night temperature structures. We conclude by suggesting important future work for still‐open questions. Plain Language Summary “Hot Jupiters” are gas giant planets, thought to be akin to Jupiter and Saturn, that orbit their parent stars with typical orbital periods of only a few days. These perplexing planets under strong stellar irradiation, found around 1% of Sun‐like stars, have been extensively studied. Here, we review many aspects of the physics of hot Jupiters. First, we discuss the leading scenarios for the formation and orbital evolution of the planets, including the dominant ideas that these planets originally form much further from their parent stars. Next, we describe models to assess their interior structure and thermal evolution and how strong stellar irradiation leads to radii that are significantly larger than that of Jupiter itself. Finally, we discuss many aspects of their atmospheres, including the opacity sources that control the temperature structure, the mass‐loss processes that drive a planetary wind, and the dynamical processes that control atmospheric circulation and day‐to‐night temperature contrasts. Key Points The origins of hot Jupiter exoplanets likely involve more than one formation pathway Explanations for the anomalously large radii of hot Jupiters need a connection to atmospheric temperature Hot Jupiters have complex atmospheres where radiation and advection both play significant roles in controlling the temperature structure