Venus' atomic hot oxygen environment

Gröller, H.; Shematovich, V. I.; Lichtenegger, Herbert; Lämmer, H.; Pfleger, Martin; Kulikov, Yu. N.; Macher, W.; Amerstorfer, Ute; Biernat, H. K.

doi:10.1029/2010je003697

Cited by 57 publications

(48 citation statements)

References 50 publications

(98 reference statements)

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“…Nagy et al, 1981;Lammer and Bauer, 1991;Kim et al, 1998;Hodges, 2000;Krestyanikova and Shematovich, 2006;Lammer et al, 2006;Gröller et al, 2010;Valeille et al, 2010). For H 2 , radiation λ < 850Å leads to either dissociation or ionization.…”

Section: The Moderate Activity Period: Solar Radiation Plasma and Mamentioning

confidence: 99%

“…For the more moderate EUV-flux period non-thermally photochemically produced suprathermal "hot" O atoms populate the exospheres of Venus and Mars. Gröller et al (2010) developed a sophisticated Monte Carlo model and applied it recently to Venus during low and high solar EUV activity. One can see from Fig.…”

Section: Response Of N 2 -Rich Atmospheres To High Euv Fluxesmentioning

confidence: 99%

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Variability of solar/stellar activity and magnetic field and its influence on planetary atmosphere evolution

et al. 2012

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It is shown that the evolution of planetary atmospheres can only be understood if one recognizes the fact that the radiation and particle environment of the Sun or a planet's host star were not always on the same level as at present. New insights and the latest observations and research regarding the evolution of the solar radiation, plasma environment and solar/stellar magnetic field derived from the observations of solar proxies with different ages will be given. We show that the extreme radiation and plasma environments of the young Sun/stars have important implications for the evolution of planetary atmospheres and may be responsible for the fact that planets with low gravity like early Mars most likely never build up a dense atmosphere during the first few 100 Myr after their origin. Finally we present an innovative new idea on how hydrogen clouds and energetic neutral atom (ENA) observations around transiting Earth-like exoplanets by space observatories such as the WSO-UV, can be used for validating the addressed atmospheric evolution studies. Such observations would enhance our understanding on the impact on the activity of the young Sun on the early atmospheres of Venus, Earth, Mars and other Solar System bodies as well as exoplanets.

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Section: The Moderate Activity Period: Solar Radiation Plasma and Mamentioning

confidence: 99%

Section: Response Of N 2 -Rich Atmospheres To High Euv Fluxesmentioning

confidence: 99%

Variability of solar/stellar activity and magnetic field and its influence on planetary atmosphere evolution

et al. 2012

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“…The CM frame parameters are stochastic values because of the thermal motion of the bath gas. The averaging over thermal motion can be done using the Boltzmann kinetic equation (Zhang et al 2008;Kharchenko et al 1997) or generating random collision parameters in the Monte Carlo simulation of the relaxation process (Gröller et al 2010). The frame-transformation procedures are especially important for a consideration of multiple collision processes, but it requires additional computational power.…”

Section: Differential Cross Sectionsmentioning

confidence: 99%

Energy Relaxation of Helium Atoms in Astrophysical Gases

Lewkow

Kharchenko

Zhang

2012

ApJ

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We report accurate parameters describing energy relaxation of He atoms in atomic gases, important for astrophysics and atmospheric science. Collisional energy exchange between helium atoms and atomic constituents of the interstellar gas, heliosphere, and upper planetary atmosphere has been investigated. Energy transfer rates, number of collisions required for thermalization, energy distributions of recoil atoms, and other major parameters of energy relaxation for fast He atoms in thermal H, He, and O gases have been computed in a broad interval of energies from 10 meV to 10 keV. This energy interval is important for astrophysical applications involving the energy deposition of energetic atoms and ions into atmospheres of planets and exoplanets, atmospheric evolution, and analysis of non-equilibrium processes in the interstellar gas and heliosphere. Angular-and energy-dependent cross sections, required for an accurate description of the momentum-energy transfer, are obtained using ab initio interaction potentials and quantum mechanical calculations for scattering processes. Calculation methods used include partial wave analysis for collisional energies below 2 keV and the eikonal approximation at energies higher than 100 eV, keeping a significant energy region of overlap, 0.1-2 keV, between these two methods for their mutual verification. The partial wave method and the eikonal approximation excellently match results obtained with each other as well as experimental data, providing reliable cross sections in the astrophysically important interval of energies from 10 meV to 10 keV. Analytical formulae, interpolating obtained energy-and angular-dependent cross sections, are presented to simplify potential applications of the reported database. Thermalization of fast He atoms in the interstellar gas and energy relaxation of hot He and O atoms in the upper atmosphere of Mars are considered as illustrative examples of potential applications of the new database.

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“…However, even in the case of Mars it can be expected that sputter loss rates are an order of magnitude lower compared, for instance, to ion pickup (e.g., Leblanc and Johnson, 2002;Chassefière and Leblanc, 2004;Lammer et al, 2013). Direct escape of heavy neutral atoms, such as O and C, as a result of photochemical processes is expected to be higher compared to ion escape from Mars (e.g., Krestyanikova and Shematovich, 2005;Chaufray et al, 2007;Fox and Hać, 2009;Lammer et al, 2013) but negligible or lower at more massive planets such as Venus (Grö ller et al, 2010 or Earth.…”

Section: Introductionmentioning

confidence: 99%

XUV-Exposed, Non-Hydrostatic Hydrogen-Rich Upper Atmospheres of Terrestrial Planets. Part II: Hydrogen Coronae and Ion Escape

et al. 2013

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We studied the interactions between the stellar wind plasma flow of a typical M star, such as GJ 436, and the hydrogen-rich upper atmosphere of an Earth-like planet and a ''super-Earth'' with a radius of 2 R Earth and a mass of 10 M Earth , located within the habitable zone at *0.24 AU. We investigated the formation of extended atomic hydrogen coronae under the influences of the stellar XUV flux (soft X-rays and EUV), stellar wind density and velocity, shape of a planetary obstacle (e.g., magnetosphere, ionopause), and the loss of planetary pickup ions on the evolution of hydrogen-dominated upper atmospheres. Stellar XUV fluxes that are 1, 10, 50, and 100 times higher compared to that of the present-day Sun were considered, and the formation of high-energy neutral hydrogen clouds around the planets due to the charge-exchange reaction under various stellar conditions was modeled. Charge-exchange between stellar wind protons with planetary hydrogen atoms, and photoionization, lead to the production of initially cold ions of planetary origin. We found that the ion production rates for the studied planets can vary over a wide range, from *1.0 · 10 25 s -1 to *5.3 · 10 30 s -1 , depending on the stellar wind conditions and the assumed XUV exposure of the upper atmosphere. Our findings indicate that most likely the majority of these planetary ions are picked up by the stellar wind and lost from the planet. Finally, we estimated the long-time nonthermal ion pickup escape for the studied planets and compared them with the thermal escape. According to our estimates, nonthermal escape of picked-up ionized hydrogen atoms over a planet's lifetime within the habitable zone of an M dwarf varies between *0.4 Earth ocean equivalent amounts of hydrogen (EO H ) to < 3 EO H and usually is several times smaller in comparison to the thermal atmospheric escape rates.

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Venus' atomic hot oxygen environment

Cited by 57 publications

References 50 publications

Variability of solar/stellar activity and magnetic field and its influence on planetary atmosphere evolution

Variability of solar/stellar activity and magnetic field and its influence on planetary atmosphere evolution

Energy Relaxation of Helium Atoms in Astrophysical Gases

XUV-Exposed, Non-Hydrostatic Hydrogen-Rich Upper Atmospheres of Terrestrial Planets. Part II: Hydrogen Coronae and Ion Escape

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