The flow of the contaminated solar wind at comet P/Grigg‐Skjellerup

Flammer, K. R.; Mendis, D. A.

doi:10.1029/93ja02530

Cited by 20 publications

(11 citation statements)

References 13 publications

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“…Unfortunately, the closest fly‐by distance was larger than the estimated size of R C . Thus, it was not possible to verify the existence or non‐existence of magnetic field‐free cavity [ Flammer and Mendis , ]. We expect that during the Rosetta mission, the formation, or the lack of, a diamagnetic cavity near a weekly‐outgassing comet will be verified.…”

Section: The Varying Particles and Fields Environment Of A Comet Orbimentioning

confidence: 99%

Dusty Plasma Effects in Comets: Expectations for Rosetta

Mendis

Horányi

2013

Reviews of Geophysics

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[1] Despite their small masses, comets have played an extraordinary role in enhancing our understanding of cosmic physics. It was the calculation of comet Halley's orbit and the successful prediction of its return in 1758 that firmly established the correctness of Newton's law of universal gravitation. It was the morphology of the dusty tails of comets that provided the earliest information of the nature of the interaction of solar electromagnetic radiation with dust, and it was the orientation and structure of the plasma tails of comets that led to the discovery of the solar wind. More recently, the role of the changing dusty plasma environments of comets as natural space laboratories for the study of dust-plasma interactions, and their physical and dynamical consequences, has been recognized. The forthcoming Rosetta-Philae rendezvous and lander mission will provide a unique opportunity to revisit the entire range of earlier observations of dusty plasma phenomena in a single comet, as it moves around the Sun. In this topical review, motivated by the Rosetta mission, we discuss the varying modes of interaction of the comet as it approaches the Sun, and the different dusty plasma phenomena that are expected in each case, drawing on the earlier observations, including their interpretations and prevailing open questions.

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Section: The Varying Particles and Fields Environment Of A Comet Orbimentioning

confidence: 99%

Dusty Plasma Effects in Comets: Expectations for Rosetta

Mendis

Horányi

2013

Reviews of Geophysics

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“…A value of 2.6−3.1 is derived from our simulations, depending on the processes taken into account. This value may be compared to the flaring ratio of 2.15 calculated by MHD models in the case of comet 1P/Halley, and subsequently applied to the Giotto measurements of comets 1P and 26P/GriggSkjellerup (Flammer & Mendis 1993). We note that our simulation's interaction region is somewhat blunter, such that the bow shock flares out on the flanks more than in the historical studies.…”

Section: Bowshockmentioning

confidence: 77%

“…(14) and (15) from the fits, are given in Table 5. The average flaring ratioF bs of the bow shock is also given; it has often been used to extrapolate satellite flyby measurements to the position of the bow shock's subsolar point (Mendis et al 1986;Flammer & Mendis 1993). …”

Section: Bowshockmentioning

confidence: 99%

Hybrid modelling of cometary plasma environments

Wedlund

Alho

Gronoff

et al. 2017

A&A

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Context. The ESA/Rosetta mission made it possible to monitor the plasma environment of a comet, from near aphelion to perihelion conditions. To understand the complex dynamics and plasma structures found at the comet, a modelling effort must be carried out in parallel. Aims. Firstly, we present a 3D hybrid model of the cometary plasma environment including photoionisation, solar wind charge exchange, and electron ionisation reactions; this model is used in stationary and dynamic conditions (mimicking the solar wind variations), and is thus especially adapted to a weakly outgassing comet such as 67P/Churyumov-Gerasimenko, the target of the ESA/Rosetta mission. Secondly, we use the model to study the respective effects of ionisation processes on the formation of the dayside macroscopic magnetic and density boundaries upstream of comet 67P in perihelion conditions at 1.3 AU. Thirdly, we explore and discuss the effects of these processes on the magnetic field line draping, ionisation rates, and composition in the context of the Rosetta mission. Methods. We used a new quasi-neutral hybrid model, originally designed for weakly magnetised planetary bodies, such as Venus, Mars, and Titan, and adapted here to comets. Ionisation processes were monitored individually and together following a probabilistic interaction scheme. Three-dimensional paraboloid fits of the bow shock surface, identified for a magnetosonic Mach number equal to 2, and of the cometopause surface, were performed for a more quantitative analysis. Results. We show that charge exchange and electron ionisation play a major role in the formation of a bow shock-like structure far upstream, while photoionisation is the main driver at and below the cometopause boundary, within 1000 km cometocentric distance. Charge exchange contributes to 42% of the total production rate in the simulation box, whereas production rates from electron ionisation and photoionisation reach 33% and 25%, respectively. We also discuss implications for Rosetta's observations, regarding the detection of the bow shock and the cometopause.

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“…Incidentally, a small ionopause radius R i (82-97) km was anticipated during the Giotto encounter of the weakly outgassing comet Grigg-Skjellerup in 1992 (Flammer & Mendis 1993;Coates et al 1993). However, these could not be verified, because the closest approach of the spacecraft to the nucleus was ∼120 km.…”

Section: The Heliocentric Variation Of the Ionopause Positionmentioning

confidence: 99%

The Global Morphology of the Solar Wind Interaction With Comet Churyumov-Gerasimenko

Mendis

Horányi

2014

ApJ

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The forthcoming Rosetta-Philae mission to comet 67P/Churyumov-Gerasimenko provides a novel opportunity to observe the variable nature of the solar wind interaction with a comet over an extended range of heliocentric distance. We use a simple analytical one-dimensional MHD model to estimate the sizes of the two most prominent features in the global structure of the solar wind interaction with a comet. When the heliocentric distance of the comet reaches d 1.51 AU, we expect a sharp shock to be observed, whose size would increase monotonically as the comet approaches the Sun, reaching a value 15,000 km at perihelion (d 1.29 AU). Upstream of the shock, we expect the velocity-space distribution of the picked up cometary ions to be essentially gyrotropic. A well-defined ionopause is predicted when d 1.61 AU, though its size is expected to be only 25 km at perihelion, and it is expected to be susceptible to the "flute" instability due to its small size. Consequently, we expect the magnetic field to penetrate all the way to the surface of the nucleus. We conclude with a brief discussion of the response of the comet's plasma environment to fast temporal variations in the solar wind.

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The flow of the contaminated solar wind at comet P/Grigg‐Skjellerup

Cited by 20 publications

References 13 publications

Dusty Plasma Effects in Comets: Expectations for Rosetta

Dusty Plasma Effects in Comets: Expectations for Rosetta

Hybrid modelling of cometary plasma environments

The Global Morphology of the Solar Wind Interaction With Comet Churyumov-Gerasimenko

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