The four final rotation states of Venus

Correia, A. C. M.; Laskar, Jacques

doi:10.1038/35081000

Cited by 145 publications

(132 citation statements)

References 23 publications

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“…Atmospheric thermal tides can result in an equilibrium rotation period that is different from the synchronized one (Correia et al 2008). This is for instance at the origin of the current rotation state of Venus (Correia & Laskar 2001). Therefore, assuming a synchronized planet may not be consistent with a dense atmosphere.…”

Section: Nonsynchronized Planetsmentioning

confidence: 99%

Thermal phase curves of nontransiting terrestrial exoplanets

Selsis

Wordsworth

Forget

2011

A&A

101

119

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Context. Although transit spectroscopy is a very powerful method for studying the composition, thermal properties, and dynamics of exoplanet atmospheres, only a few transiting terrestrial exoplanets will be close enough to allow significant transit spectroscopy with the current and forthcoming generations of instruments. Thermal phase curves (variations in the apparent infrared emission of the planet with its orbital phase) have been observed for hot Jupiters in both transiting and nontransiting configurations, and have been used to put constraints on the temperature distribution and atmospheric circulation. This method could be applied to hot terrestrial exoplanets. Aims. We study the wavelength and phase changes of the thermal emission of a tidally-locked terrestrial planet as atmospheric pressure increases. We address the observability of these multiband phase curves and the ability to use them to detect atmospheric constituents. Methods. We used a 3D climate model (GCM) to simulate the CO 2 atmosphere of a terrestrial planet on an 8-day orbit around an M 3 dwarf and its apparent infrared emission as a function of its orbital phase. We estimated the signal to photon-noise ratio in narrow bands between 2.5 and 20 μm for a 10 pc target observed with a 6 m and a 1.5 m telescope (respectively the sizes of JWST and EChO). Results. Atmospheric absorption bands produce associated signatures in what we call the variation spectrum. Atmospheric windows probing the near surface atmospheric layers are needed to produce large, observable phase-curve amplitudes. The number and transparency of these windows, hence the observability of the phase curves and the molecular signatures, decreases with increasing pressure. Planets with no atmosphere produce large variations and can be easily distinguished from dense absorbing atmospheres. Conclusions. Photon-noise limited spectro-photometry of nearby systems could allow us to detect and characterize the atmosphere of nontransiting terrestrial planets known from radial velocity surveys. Two obvious impediments to these types of observations are the required photometric sensitivity (10 −5 ) over the duration of at least one orbit (8-days in the studied case) and the intrinsic stellar variability. However, overcoming these obstacles would give access to one order of magnitude more targets than does transit spectroscopy.

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Section: Nonsynchronized Planetsmentioning

confidence: 99%

Thermal phase curves of nontransiting terrestrial exoplanets

Selsis

Wordsworth

Forget

2011

A&A

101

119

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“…There have already been many studies on the rotation of Venus. Several authors have studied this rotation on a long time scale to understand why Venus' spin is retrograde and why its spin axis has low obliquity (Goldstein 1964;Carpenter 1964;Goldreich & Peale 1970;Lago & Cazenave 1979;Dobrovoskis 1980;Yoder 1995;Correia & Laskar 2001, 2003. Others studied the possible resonance between the Earth and Venus (Gold & Soter 1979;Bills 2005;Bazsó et al 2010).…”

Section: Introductionmentioning

confidence: 99%

The various contributions in Venus rotation rate and LOD

Cottereau

Rambaux

Lebonnois

et al. 2011

A&A

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Context. Thanks to the Venus Express Mission, new data on the properties of Venus could be obtained, in particular concerning its rotation. Aims. In view of these upcoming results, the purpose of this paper is to determine and compare the major physical processes influencing the rotation of Venus and, more particularly, the angular rotation rate. Methods. Applying models already used for Earth, the effect of the triaxiality of a rigid Venus on its period of rotation are computed. Then the variations of Venus rotation caused by the elasticity, the atmosphere, and the core of the planet are evaluated. Results. Although the largest irregularities in the rotation rate of the Earth on short time scales are caused by its atmosphere and elastic deformations, we show that the irregularities for Venus are dominated by the tidal torque exerted by the Sun on its solid body. Indeed, as Venus has a slow rotation, these effects have a large amplitude of two minutes of time (mn). These variations in the rotation rate are greater than the one induced by atmospheric wind variations that can reach 25-50 s of time (s), depending on the simulation used. The variations due to the core effects that vary with its size between 3 and 20 s are smaller. Compared to these effects, the influence of the elastic deformation caused by the zonal tidal potential is negligible. Conclusions. As the variations in the rotation of Venus reported here are close to 3 mn peak to peak, they should influence past, present, and future observations, thereby providing further constraints on the planet's internal structure and atmosphere.

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“…If that occurred, the torque from Earth could dominate and spin-lock Venus to the Earth (Gold and Soter, 1969). More recent and detailed work has shown that this interaction can be significant and permits chaotic spin evolution that eventually settles into one of four possible states (Correia and Laskar, 2001). Although a large atmosphere can play a significant role in the evolution of terrestrial planets (Correia and Laskar, 2003), we ignore their effect here due to the large number of unknowns for an exoplanet.…”

Section: E4 Tidal Response In Celestial Bodiesmentioning

confidence: 99%

Tidal Venuses: Triggering a Climate Catastrophe via Tidal Heating

et al. 2013

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Traditionally, stellar radiation has been the only heat source considered capable of determining global climate on long timescales. Here, we show that terrestrial exoplanets orbiting low-mass stars may be tidally heated at highenough levels to induce a runaway greenhouse for a long-enough duration for all the hydrogen to escape. Without hydrogen, the planet no longer has water and cannot support life. We call these planets ''Tidal Venuses'' and the phenomenon a ''tidal greenhouse.'' Tidal effects also circularize the orbit, which decreases tidal heating. Hence, some planets may form with large eccentricity, with its accompanying large tidal heating, and lose their water, but eventually settle into nearly circular orbits (i.e., with negligible tidal heating) in the habitable zone (HZ). However, these planets are not habitable, as past tidal heating desiccated them, and hence should not be ranked highly for detailed follow-up observations aimed at detecting biosignatures. We simulated the evolution of hypothetical planetary systems in a quasi-continuous parameter distribution and found that we could constrain the history of the system by statistical arguments. Planets orbiting stars with masses < 0.3 M Sun may be in danger of desiccation via tidal heating. We have applied these concepts to Gl 667C c, a *4.5 M Earth planet orbiting a 0.3 M Sun star at 0.12 AU. We found that it probably did not lose its water via tidal heating, as orbital stability is unlikely for the high eccentricities required for the tidal greenhouse. As the inner edge of the HZ is defined by the onset of a runaway or moist greenhouse powered by radiation, our results represent a fundamental revision to the HZ for noncircular orbits. In the appendices we review (a) the moist and runaway greenhouses, (b) hydrogen escape, (c) stellar mass-radius and mass-luminosity relations, (d) terrestrial planet mass-radius relations, and (e) linear tidal theories.

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The four final rotation states of Venus

Cited by 145 publications

References 23 publications

Thermal phase curves of nontransiting terrestrial exoplanets

Thermal phase curves of nontransiting terrestrial exoplanets

The various contributions in Venus rotation rate and LOD

Tidal Venuses: Triggering a Climate Catastrophe via Tidal Heating

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