Stochastic models of hot planetary and satellite coronas: a photochemical source of hot Oxygen in the upper atmosphere of Mars

Krestyanikova, M. A.; Shematovich, V. I.

doi:10.1007/s11208-005-0002-9

Cited by 31 publications

(46 citation statements)

References 56 publications

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“…Relaxation times, computed with the isotropic HS model (Bondi 1964), are also shown in Figure 10. These HS results are drastically different from results obtained with actual quantum cross sections (Fox & Hać 2009;Krest'yanikova & Shematovich 2005;Shizgal 1999;Kharchenko et al 1997), differing in relaxation times by approximately two orders of magnitude. The evaluated energy relaxation times are useful for analysis of the relative contributions of different constituents into the atmospheric energy relaxation process.…”

Section: Energy Exchange Between Hot Atoms and Thermal Gases In The Ucontrasting

confidence: 95%

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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Section: Energy Exchange Between Hot Atoms and Thermal Gases In The Ucontrasting

confidence: 95%

Energy Relaxation of Helium Atoms in Astrophysical Gases

Lewkow

Kharchenko

Zhang

2012

ApJ

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“…Both 1-D and 3-D exosphere models, with widely varying complexity, have recently been used to simulate the hot atomic O distribution as well as the corresponding escape fluxes and global escape rates (e.g. Kim et al 2001;Hodges 2002;Krestyanikova and Shematovitch 2005;Cipriani et al 2007;Chaufray et al 2007;Valeille et al , 2009bValeille et al , 2010aValeille et al , 2010bYagi et al 2012). Fox and Hać (2009) also compute hot O escape fluxes and global escape rates.…”

Section: What Are the Global Distributions Of Hot (Suprathermal) Neutmentioning

confidence: 99%

The Aeronomy of Mars: Characterization by MAVEN of the Upper Atmosphere Reservoir That Regulates Volatile Escape

et al. 2014

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The Mars thermosphere-ionosphere-exosphere (TIE) system constitutes the atmospheric reservoir (i.e. available cold and hot planetary neutral and thermal ion species) that regulates present day escape processes from the planet. The characterization of this TIE system, including its spatial and temporal (e.g., solar cycle, seasonal, diurnal, episodic) variability is needed to determine present day escape rates. Without knowledge of the physics and chemistry creating this TIE region and driving its variations, it is not possible to constrain either the short term or long term histories of atmosphere escape from Mars. MAVEN (Mars Atmosphere and Volatile Evolution Mission) will make both in-situ and remote measurements of the state variables of the Martian TIE system. A full characterization of the thermosphere (∼100-250 km) and ionosphere (∼100-400 km) structure (and its variability) will be conducted with the collection of spacecraft in-situ measurements that systematically span most local times and latitudes, over a regular sampling of Mars seasons, and throughout the bottom half of the solar cycle. Such sampling will far surpass that available from existing spacecraft and ground-based datasets. In addition, remote measurements will provide a systematic mapping of the composition and structure of Mars neutral upper atmosphere and coronae (e.g. H, C, N, O), as well as probe lower altitudes. Such a detailed characterization is a necessary first step toward answering MAVEN's three main science questions (see Jakosky et al. 2014, this issue). This information will be used to determine present day escape rates from Mars, and provide an estimate of integrated loss to space throughout Mars history.

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“…In this study the suprathermal particles are assumed to become thermalized via elastic collisions only. This may result in some underestimation of the thermalization rate due to the neglect of the excitation of rotational and vibrational levels of the molecules in inelastic collisions with hot O atoms [Krestyanikova and Shematovich, 2005]. The total cross section for elastic collisions between ground state oxygen atoms averaged over a statistical population of O( 3 P) fine structure levels can be represented by the semiclassical Landau-Schiff formula [Kharchenko et al, 2000] and is applied in the present calculations ( Figure 2).…”

Section: Collision Parametersmentioning

confidence: 99%

On the elusive hot oxygen corona of Venus

Lichtenegger

Gröller

Lämmer

et al. 2009

Geophysical Research Letters

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[1] After more than two years in orbit still no Venus Express observations were published concerning the hot oxygen corona of Venus which could verify the corresponding controversial observations of Venera 11 and PVO, three decades ago. Based on recent energy and mass dependent collision cross sections, the energy distributions of hot atomic oxygen created via dissociative recombination of O 2 + are calculated in the daytime thermosphere by means of a 3D Monte Carlo approach. The exosphere density is obtained from the corresponding energy density and angular distribution at 240 km altitude by using a test particle model which traces the ballistic trajectories of hot O atoms in the exosphere. Our study indicates that upon taking into account proper input parameters, the hot oxygen corona appears to be substantially less dense than suggested by previous simulations. Citation: Lichtenegger, H. I. M., H.

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Stochastic models of hot planetary and satellite coronas: a photochemical source of hot Oxygen in the upper atmosphere of Mars

Cited by 31 publications

References 56 publications

Energy Relaxation of Helium Atoms in Astrophysical Gases

Energy Relaxation of Helium Atoms in Astrophysical Gases

The Aeronomy of Mars: Characterization by MAVEN of the Upper Atmosphere Reservoir That Regulates Volatile Escape

On the elusive hot oxygen corona of Venus

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