Widely different characteristics of oxygen and hydrogen ion escape from Venus

Järvinen, R.; Kallio, Esa; Dyadechkin, Sergey; Janhunen, P.; Sillanpää, I.

doi:10.1029/2010gl044062

Cited by 15 publications

(24 citation statements)

References 16 publications

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“…The spatial distribution of these ions are, therefore, quite different near Venus, the Venusian magnetosphere acting much like an ion "mass filter". It is worthy of emphasis that different ion trajectories are an FLR effect, and the trajectories of the magnetized light ions (m p and 4m p ) follow in the first approximation V E×B motion while the heavy ions (16m p and 32m p ) are practically non-magnetized and do not follow the V E×B motion (Jarvinen et al, 2010a).…”

Section: The Motion Of Escaping Planetary Ionsmentioning

confidence: 99%

“…It is well established that in the HYB-model the large ion gyroradii of planetary O + and O 2 + ions result in a situation where the heavy planetary ions originating near the planet are accelerated toward the +E sw hemisphere due to the convective electric field at Mars (see, e.g. Kallio et al, 2010) and at Venus (Jarvinen et al, 2010a). Recently, more general interest in how the different m/q ratio of planetary ions affects the escape pattern has, however, arisen due to the ASPERA-4 H + and O + observations at Venus (Barabash et al, 2007).…”

Section: The Motion Of Escaping Planetary Ionsmentioning

confidence: 99%

“…Both Venusian and Martian plasma environments have previously been simulated with the HYB family models. Comprehensive details of the HYB versions for Mars (HYB-Mars) and Venus (HYB-Venus) can be found in Kallio et al (2010), in Jarvinen et al (2010a) and in references therein. Here we summarize only the basic features of the HYB models.…”

Section: Global Numerical Modelsmentioning

confidence: 99%

“…2 the role of the m/q ratio is studied by test particle simulation where the electromagnetic field is obtained from the HYB-Venus model (see Jarvinen et al, 2010a, about the details of the used Venus run). In Fig.…”

Section: The Motion Of Escaping Planetary Ionsmentioning

confidence: 99%

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Kinetic effects on ion escape at Mars and Venus: Hybrid modeling studies

Kallio

Järvinen

2012

Earth Planet Sp

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Kinetic effects are anticipated to play a role at Mars and Venus when the escape of planetary ions is considered because of the large ion gyroradius compared with the size of the planets. In this paper we have used the HYB hybrid model to analyze the role of kinetic effects at these non-magnetized planets by varying the mass of ions in the simulation. The test runs suggest that kinetic effects should be taken into account when properties and formation of the planetary three dimensional plasma and electromagnetic field environment are studied.

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Section: The Motion Of Escaping Planetary Ionsmentioning

confidence: 99%

Section: The Motion Of Escaping Planetary Ionsmentioning

confidence: 99%

Section: Global Numerical Modelsmentioning

confidence: 99%

Section: The Motion Of Escaping Planetary Ionsmentioning

confidence: 99%

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Kinetic effects on ion escape at Mars and Venus: Hybrid modeling studies

Kallio

Järvinen

2012

Earth Planet Sp

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“…11) that include more of the physics of the ion acceleration and spatial distributions (e.g. see Jarvinen et al 2010Jarvinen et al , 2016 have made further progress in untangling the complicated planetary ion magnetotail of Venus.…”

Section: Plasma In the Magnetotailmentioning

confidence: 99%

Solar Wind Interaction and Impact on the Venus Atmosphere

et al. 2017

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Venus has intrigued planetary scientists for decades because of its huge contrasts to Earth, in spite of its nickname of "Earth's Twin". Its invisible upper atmosphere and space environment are also part of the larger story of Venus and its evolution. In 60s to 70s, several missions (Venera and Mariner series) explored Venus-solar wind interaction regions. They identified the basic structure of the near-Venus space environment, for example, existence of the bow shock, magnetotail, ionosphere, as well as the lack of the intrinsic magnetic field. A huge leap in knowledge about the solar wind interaction with Venus was made possible by the 14-year long mission, Pioneer Venus Orbiter (PVO), launched in 1978. More recently, ESA's probe, Venus Express (VEX), was inserted into orbit in 2006, operated for 8 years.Owing to its different orbit from that of PVO, VEX made unique measurements in the polar and terminator regions, and probed the near-Venus tail for the first time. The near-tail hosts dynamic processes that lead to plasma energization. These processes in turn lead to the loss of ionospheric ions to space, slowly eroding the Venusian atmosphere. VEX carried an ion spectrometer with a moderate mass-separation capability and the observed ratio of the escaping hydrogen and oxygen ions in the wake indicates the stoichiometric loss of water from Venus. The structure and dynamics of the induced magnetosphere depends on the prevailing solar wind conditions. VEX studied the response of the magnetospheric system on different time scales. A plethora of waves was identified by the magnetometer on VEX; some of them were not previously observed by PVO. Proton cyclotron waves were seen far upstream of the bow shock, mirror mode waves were observed in magnetosheath and whistler mode waves, possibly generated by lightning discharges were frequently seen. VEX also encouraged renewed numerical modeling efforts, including fluid-type of models and particle-fluid hybrid type of models, describing the plasma interaction on scales ranging from ion gyro radius to the entire induced magnetosphere. In this review article, we review what has been found from space physics measurements around Venus (from the solar wind down to the ionopause), with a particular emphasis on updated results since the Venus Express mission. We conclude the article by a short discussion on the remaining open scientific questions and the future of this field.

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Energization of planetary pickup ions in the solar system

Järvinen

Kallio

2014

JGR Planets

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We study the solar wind-induced ion escape from planetary atmospheres at different radial heliospheric distances in the solar system. We derive histograms of the gyroaveraged E × B velocities, energies, and Larmor radii of planetary ions in the solar wind at Mercury, Venus, Earth, and Mars. The statistical analysis is based on the interplanetary Pioneer Venus Orbiter and OMNI solar wind data sets. In addition to the energization in the undisturbed solar wind we also model how planetary heavy ions get energized in the solar wind interaction of an unmagnetized planet at different distances to the Sun. We found that due to the Parker spiral, pickup ions are expected to be found on average at lower energies and at velocities more perpendicular to the solar wind flow, the closer to the Sun a planet or a comet is. According to a global hybrid simulation, planetary heavy ion energization is influenced qualitatively in a similar way in the presence of an induced magnetosphere than in the upstream solar wind under different Parker spiral angles due to fact that the structure of an induced magnetosphere depends strongly on the interplanetary magnetic field and solar wind conditions. Finally, the energization and dynamics of the pickup ions vary considerably with the solar activity. The variation is stronger the farther away from the Sun an object is. The Larmor radii of the pickup ions are largest during a solar minimum while the pickup ion energies are highest during the declining phase of a solar cycle.

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Widely different characteristics of oxygen and hydrogen ion escape from Venus

Cited by 15 publications

References 16 publications

Kinetic effects on ion escape at Mars and Venus: Hybrid modeling studies

Kinetic effects on ion escape at Mars and Venus: Hybrid modeling studies

Solar Wind Interaction and Impact on the Venus Atmosphere

Energization of planetary pickup ions in the solar system

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