Nonequilibrium aeronomic processes

Marov, Mikhail Ya.; Shematovich, V. I.; Bisicalo, Dmitry V.

doi:10.1007/bf00240583

Cited by 29 publications

(17 citation statements)

References 169 publications

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“…The resulting observational manifestations of hot atoms confirmed theoretical predictions of the important role of nonequilibrium processes involving suprathermal particles in planetary atmospheres [239]. A new direction in planetary aeronomy is currently being actively developed: investigation of the role of suprathermal particles in the physics and chemistry of planetary atmospheres [239][240][241]. It follows from the most important results of such studies that suprathermal (hot) particles in excited states forming in the upper layers of atmospheres give rise to non-thermal atmospheric emission and enhance non-thermal atmospheric losses, thereby determining the evolution of the atmosphere on astronomical time scales.…”

Section: Atmospheres Of Planets and Small Bodies In The Solar Systemsupporting

confidence: 67%

“…These processes are accompanied by an intense transfer of energy between various degrees of freedom of the atmospheric particles and the substantial thermal effect of photochemical reactions. The resulting observational manifestations of hot atoms confirmed theoretical predictions of the important role of nonequilibrium processes involving suprathermal particles in planetary atmospheres [239]. A new direction in planetary aeronomy is currently being actively developed: investigation of the role of suprathermal particles in the physics and chemistry of planetary atmospheres [239][240][241].…”

Section: Atmospheres Of Planets and Small Bodies In The Solar Systemmentioning

confidence: 52%

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Scientific problems addressed by the Spektr-UV space project (world space Observatory—Ultraviolet)

et al. 2016

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Abstract-The article presents a review of scientific problems and methods of ultraviolet astronomy, focusing on perspective scientific problems (directions) whose solution requires UV space observatories. These include reionization and the history of star formation in the Universe, searches for dark baryonic matter, physical and chemical processes in the interstellar medium and protoplanetary disks, the physics of accretion and outflows in astrophysical objects, from Active Galactic Nuclei to close binary stars, stellar activity (for both low-mass and high-mass stars), and processes occurring in the atmospheres of both planets in the solar system and exoplanets. Technological progress in UV astronomy achieved in recent years is also considered. The well advanced, international, Russian-led Spektr-UV (World Space Observatory-Ultraviolet) project is described in more detail. This project is directed at creating a major space observatory operational in the ultraviolet (115-310 nm). This observatory will provide an effective, and possibly the only, powerful means of observing in this spectral range over the next ten years, and will be an powerful tool for resolving many topical scientific problems.

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Section: Atmospheres Of Planets and Small Bodies In The Solar Systemsupporting

confidence: 67%

Section: Atmospheres Of Planets and Small Bodies In The Solar Systemmentioning

confidence: 52%

Scientific problems addressed by the Spektr-UV space project (world space Observatory—Ultraviolet)

et al. 2016

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“…This model includes the reactions (2) and the transport of suprathermal electrons. The energy of a secondary electron formed during a collision and subsequent ionization is chosen following the procedure described in Marov et al (1996);Shematovich (2008Shematovich ( , 2010.…”

Section: Modelmentioning

confidence: 99%

Survival of a planet in short-period Neptunian desert under effect of photoevaporation

Ionov

Pavlyuchenkov

Shematovich

2018

Monthly Notices of the Royal Astronomical Society

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Despite the identification of a great number of Jupiter-like and Earth-like planets at close-in orbits, the number of "hot Neptunes" -the planets with 0.6-18 times of Neptune mass and orbital periods less than 3 days -turned out to be very small. The corresponding region in the mass-period distribution was assigned as the "shortperiod Neptunian desert". The common explanation of this fact is that the gaseous planet with few Neptune masses would not survive in the vicinity of host star due to intensive atmosphere outflow induced by heating from stellar radiation. To check this hypothesis we performed numerical simulations of atmosphere dynamics for a hot Neptune. We adopt the previously developed self-consistent 1D model of hydrogenhelium atmosphere with suprathermal electrons accounted. The mass-loss rates as a function of orbital distances and stellar ages are presented. We conclude that the desert of short-period Neptunes could not be entirely explained by evaporation of planet atmosphere caused by the radiation from a host star. For the less massive Neptune-like planet, the estimated upper limits of the mass loss may be consistent with the photo-evaporation scenario, while the heavier Neptune-like planets could not lose the significant mass through this mechanism. We also found the significant differences between our numerical results and widely used approximate estimates of the mass loss.

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“…The DSMC method is an efficient tool to solve atmospheric kinetic systems in the stochastic approximation (Shematovich et al 1994;Bisikalo et al 1995;Marov et al 1996;Gérard et al 2000). The details of the algorithmic realization of the numerical model were given earlier (Shematovich et al 1994;Bisikalo et al 1995;Shematovich 2010).…”

Section: Numerical Modelmentioning

confidence: 99%

Heating efficiency in hydrogen-dominated upper atmospheres

Shematovich

Ionov

Lämmer

2014

A&A

120

106

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Context. The heating efficiency η hν is defined as the ratio of the net local gas-heating rate to the rate of stellar radiative energy absorption. It plays an important role in thermal-escape processes from the upper atmospheres of planets that are exposed to stellar soft X-rays and extreme ultraviolet radiation (XUV). Aims. We model the thermal-escape-related heating efficiency η hν of the stellar XUV radiation in the hydrogen-dominated upper atmosphere of the extrasolar gas giant HD 209458b. The model result is then compared with previous thermal-hydrogen-escape studies, which assumed η hν values between 10-100%. Methods. The photolytic and electron impact processes in the thermosphere were studied by solving the kinetic Boltzmann equation and applying a Direct Simulation Monte Carlo model. We calculated the energy deposition rates of the stellar XUV flux and that of the accompanying primary photoelectrons that are caused by electron impact processes in the H 2 → H transition region in the upper atmosphere. Results. The heating by XUV radiation of hydrogen-dominated upper atmospheres does not reach higher values than 20% above the main thermosphere altitude, if the participation of photoelectron impact processes is included. Conclusions. Hydrogen-escape studies from exoplanets that assume η hν values that are ≥20% probably overestimate the thermal escape or mass-loss rates, while those who assumed values that are <20% produce more realistic atmospheric-escape rates.

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Nonequilibrium aeronomic processes

Cited by 29 publications

References 169 publications

Scientific problems addressed by the Spektr-UV space project (world space Observatory—Ultraviolet)

Scientific problems addressed by the Spektr-UV space project (world space Observatory—Ultraviolet)

Survival of a planet in short-period Neptunian desert under effect of photoevaporation

Heating efficiency in hydrogen-dominated upper atmospheres

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