Venus' rotation and atmospheric tides

Ingersoll, Andrew P.; Dobrovolskis, Anthony R.

doi:10.1038/275037a0

Cited by 75 publications

(70 citation statements)

References 4 publications

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“…(156) because convection eliminates the component resulting from the fluid vertical displacement. In agreement with the early result of Ingersoll & Dobrovolskis (1978) (Eq. (4)), it is of the same form as the result given by the Maxwell model (Correia et al 2014), where we identify the Maxwell time T 0 " σ´1 0 .…”

Section: Comparison With Previous Modelssupporting

confidence: 81%

Atmospheric tides in Earth-like planets

Auclair-Desrotour

Laskar

Mathis

2017

A&A

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Context. Atmospheric tides can strongly affect the rotational dynamics of planets. In the family of Earth-like planets, which includes Venus, this physical mechanism coupled with solid tides makes the angular velocity evolve over long timescales and determines the equilibrium configurations of their spin. Aims. Unlike the solid core, the atmosphere of a planet is subject to both tidal gravitational potential and insolation flux coming from the star. The complex response of the gas is intrinsically linked to its physical properties. This dependence has to be characterized and quantified for application to the wide variety of extrasolar planetary systems. Methods. We develop a theoretical global model where radiative losses, which are predominant in slowly rotating atmospheres, are taken into account. We analytically compute the perturbation of pressure, density, temperature, and velocity field caused by a thermogravitational tidal perturbation. From these quantities, we deduce the expressions of atmospheric Love numbers and tidal torque exerted on the fluid shell by the star. The equations are written for the general case of a thick envelope and the simplified one of a thin isothermal atmosphere. Results. The dynamics of atmospheric tides depends on the frequency regime of the tidal perturbation: the thermal regime near synchronization and the dynamical regime characterizing fast-rotating planets. Gravitational and thermal perturbations imply different responses of the fluid, i.e. gravitational tides and thermal tides, which are clearly identified. The dependence of the torque on the tidal frequency is quantified using the analytic expressions of the model for Earth-like and Venus-like exoplanets and is in good agreement with the results given by global climate models (GCM) simulations. Introducing dissipative processes such as radiation regularizes the tidal response of the atmosphere, otherwise it is singular at synchronization. Conclusions. We demonstrate the important role played by the physical and dynamical properties of a super-Earth atmosphere (e.g. Coriolis, stratification, basic pressure, density, temperature, radiative emission) in its response to a tidal perturbation. We point out the key parameters defining tidal regimes (e.g. inertia, Brunt-Väisälä, radiative frequencies, tidal frequency) and characterize the behaviour of the fluid shell in the dissipative regime, which cannot be studied without considering the radiative losses.

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Section: Comparison With Previous Modelssupporting

confidence: 81%

Atmospheric tides in Earth-like planets

Auclair-Desrotour

Laskar

Mathis

2017

A&A

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“…Additionally, thermal atmospheric tides raised on a close orbiting planet could be significant compared to gravitational tides (Gold & Soter, 1969;Ingersoll & Dobrovolskis, 1978;Leconte et al, 2015;Cunha et al, 2015). Recent work exploring the effect of thermal tides in the atmospheres of M-dwarf planets indicates that for high stellar insolation, an atmospheric torque may be generated that opposes tidally-induced spin synchronization, as is the case for Venus.…”

Section: Gravitational Effectsmentioning

confidence: 99%

The habitability of planets orbiting M-dwarf stars

2016

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The prospects for the habitability of M-dwarf planets have long been debated, due to key differences between the unique stellar and planetary environments around these low-mass stars, as compared to hotter, more luminous Sunlike stars. Over the past decade, significant progress has been made by both space-and ground-based observatories to measure the likelihood of small planets to orbit in the habitable zones of M-dwarf stars. We now know that most M dwarfs are hosts to closely-packed planetary systems characterized by a paucity of Jupiter-mass planets and the presence of multiple rocky planets, with roughly a third of these rocky M-dwarf planets orbiting within the habitable zone, where they have the potential to support liquid water on their surfaces. Theoretical studies have also quantified the effect on climate and habitability of the interaction between the spectral energy distribution of M-dwarf stars and the atmospheres and surfaces of their planets. These and other recent results fill in knowledge gaps that existed at the time of the previous overview papers published nearly a decade ago by Tarter et al. (2007) and Scalo et al. (2007). In this review we provide a comprehensive picture of the current knowledge of M-dwarf planet occurrence and habitability based on work done in this area over the past decade, and summarize future directions planned in this quickly evolving field.

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“…The first possibility is that the gravitational torque on the atmosphere pushes the atmosphere away from synchronous rotation (i.e., it increases the magnitude of the atmosphere's angular momentum measured in the synchronously-rotating reference frame) as has been hypothesized for Venus (Ingersoll & Dobrovolskis 1978;Gold & Soter 1969). To balance the torque on the atmosphere, the interior must have a net angular momentum of the same sign as the atmosphere (so that both either superor subrotate).…”

Section: The Equilibrium Statementioning

confidence: 99%

Atmospheric circulation and tides of “51 Pegasus b-like” planets

Showman¹,

Guillot

2002

A&A

584

609

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Abstract.We examine the properties of the atmospheres of extrasolar giant planets at orbital distances smaller than 0.1 AU from their stars. We show that these "51 Peg b-like" planets are rapidly synchronized by tidal interactions, but that small departures from synchronous rotation can occur because of fluid-dynamical torques within these planets. Previous radiative-transfer and evolution models of such planets assume a homogeneous atmosphere. Nevertheless, we show using simple arguments that, at the photosphere, the day-night temperature difference and characteristic wind speeds may reach ∼500 K, and ∼2 km s −1 , respectively. Substantial departures from chemical equilibrium are expected. The cloud coverage depends sensitively on the dynamics; clouds could exist predominantly either on the dayside or nightside, depending on the circulation regime. Radiative-transfer models that assume homogeneous conditions are therefore inadequate in describing the atmospheric properties of 51 Peg b-like planets. We present preliminary three-dimensional, nonlinear simulations of the atmospheric circulation of HD 209458b that indicate plausible patterns for the circulation and generally agree with our simpler estimates. Furthermore, we show that kinetic energy production in the atmosphere can lead to the deposition of substantial energy in the interior, with crucial consequences for the evolution of these planets. Future measurements of reflected and thermally-emitted radiation from these planets will help test our ideas.

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Venus' rotation and atmospheric tides

Cited by 75 publications

References 4 publications

Atmospheric tides in Earth-like planets

Atmospheric tides in Earth-like planets

The habitability of planets orbiting M-dwarf stars

Atmospheric circulation and tides of “51 Pegasus b-like” planets

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