Solar Wind Flow with Hydrogen Pickup

Khabibrakhmanov, I. Kh.; Summers, Danny; Zank, G. P.; Pauls, H. L.

doi:10.1086/177839

Cited by 19 publications

(18 citation statements)

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“…Since the plasma beta in the outer heliosphere is large, thanks to the dominant PUI pressure, we can for the present purposes neglect the interplanetary magnetic field and consider a single‐fluid one‐dimensional (1‐D) hydrodynamic model with charge‐exchange [ Holzer , 1972; Khabibrakhmanov et al , 1996; Zank , 1999], where ψ = (ρ, u , P ) t denotes the plasma density, velocity and pressure of the solar wind, respectively, 〈σ〉 ≃ 5 × 10 −15 cm −2 is the averaged charge‐exchange cross section, N ∼ 0.1 cm −3 is the interstellar neutral hydrogen number density in the outer heliosphere, and γ = 5/3, appropriate to strong scattering of the PUIs, is assumed. The source terms are approximations for the supersonic solar wind.…”

Section: Theorymentioning

confidence: 99%

Velocity oscillations in the outer heliosphere: A signature of pickup ion temperature variability?

Zank

Richardson

2005

J. Geophys. Res.

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[1] Unusual long wavelength (0.5-1 AU), low-frequency ($3 Â 10 À5 s À1 ) velocity oscillations have been observed by Voyager 2 at 48 AU in the outer heliosphere (Paularena et al., 1996). The velocity oscillations appear to be superimposed on weak linear velocity gradients that are typically increasing. To date, no explanation has been advanced for the origin of either the flow gradients or the oscillations. Here we show that pickup ions can excite low-frequency fluctuations and drive the flow field linearly. The model is compared directly to velocity oscillations observed by the Voyager 2 PLS instrument between 40 and 55 AU over the 6-year period 1993-1998.Citation: Zank, G. P., X. Ao, and J. D. Richardson (2005), Velocity oscillations in the outer heliosphere: A signature of pickup ion temperature variability?,

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Section: Theorymentioning

confidence: 99%

Velocity oscillations in the outer heliosphere: A signature of pickup ion temperature variability?

Zank

Richardson

2005

J. Geophys. Res.

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“…The only assumption that is needed is for the value of the adiabatic index (γ= 2 corresponds to no‐scattering of the PUI distribution, γ= 5/3 corresponds to scattering of the PUIs on to a shell distribution; see e.g. Khabibrakhmanov et al 1996 or section 4.1 of Zank 1999a). The pickup of ions and the creation of new H atoms are included self‐consistently through source integrals in the plasma momentum and energy equations (Holzer 1972; Pauls, Zank & Williams 1995).…”

Section: Introductionmentioning

confidence: 99%

Realistic and time-varying outer heliospheric modelling

Washimi

Zank

et al. 2011

Monthly Notices of the Royal Astronomical Society

107

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We develop a realistic and time‐varying model that satisfies both the Voyager 1 (V1) and Voyager 2 (V2) observed crossing times and locations of the termination shock (TS) simultaneously by performing three‐dimensional (3D) magnetohydrodynamic (MHD) simulations using a total variation diminishing (TVD) scheme that includes the effects of neutral particles. Daily values of solar‐wind speed and density observed by V2 are used at every simulation step so that short‐term dynamical effects are reproduced. Before performing the dynamic simulation, we generate a 3D stationary solution using a set of standard parameters: the interstellar proton density is assumed to be 0.061 cc−1, the interstellar neutral hydrogen density 0.176 cc−1, the interstellar medium speed relative to the Sun 26.3 km s−1 and a temperature of 6300 K. The interstellar magnetic field intensity is 0.3 nT and the orientation is oblique to the flow direction lying in the hydrogen deflection plane. The anisotropy of the solar‐wind speed is also taken into account using 400 km s−1 at low latitudes and 1.5 times faster at high latitudes. A solar‐wind density at 1 au of 3.55 cc−1 and a latitudinal angle separating the high/low solar‐wind speed regions of 80° yield dynamic solutions, starting from the stationary solution, that satisfy the V1 and V2 crossing times and locations. Our simulations clearly show that (i) the TS position increases whenever a solar‐wind high‐ram‐pressure pulse collides with the TS; (ii) a large‐amplitude magneto‐sonic pulse is generated downstream of the TS when a solar‐wind high‐ram‐pressure pulse collides with the TS; (iii) fine structure in the heliosheath is present, corresponding to a magnetic wall and plasma sheet near the heliopause (HP), and a thin current sheet; (iv) the magneto‐sonic pulse is reflected at the plasma sheet in the heliosheath, and the TS position decreases when the reflected pulse collides with the TS and (v) the time‐varying radial distance between V2 and simulated TS positions appears to be consistent with the TS particle intensity profile during the period when the TS particles were observed at V2. This last point, together with the overwhelming consistency of our MHD results with a standard set of solar‐wind and local interstellar medium (LISM) parameters, suggests that the outer heliosphere is controlled essentially by MHD and neutral interstellar gas processes, although V2 observations of solar‐wind plasma in the heliosheath are not well reproduced in our simulations.

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“…However, collisional frequencies are so low for the SW that we may neglect these collisional terms and treat the distribution function (10) as "frozen" into the plasma. Even though the solar wind is effectively collisionless, an MHD approach is still warranted since the plasma has fluid properties perpendicular to the magnetic field, while various wave phenomena help isotropize the distribution (see for example Khabibrakhmanov et al 1996;Kulsrud 1984). For these reasons, solve the regular MHD equations to determine the bulk plasma quantities, but in the inner heliosheath they interpret these as having come from (10).…”

Section: Mathematical Formulation For Modeling the Solar Wind-lism Inmentioning

confidence: 99%

Physics of the Solar Wind–Local Interstellar Medium Interaction: Role of Magnetic Fields

et al. 2009

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The interaction of the solar wind with the local interstellar medium is characterized by the self-consistent coupling of solar wind plasma, both upstream and downstream of the heliospheric termination shock, the interstellar plasma, and the neutral atom component of interstellar and solar wind origin. The complex coupling results in the creation of new plasma components (pickup ions), turbulence, and anomalous cosmic rays, and new populations of neutral atoms and their coupling can lead to energetic neutral atoms that can be detected at 1 AU. In this review, we discuss the interaction and coupling of global sized structures (the heliospheric boundary regions) and kinetic physics (the distributions that are responsible for the creation of energetic neutral atoms) based on models that have been developed by the University of Alabama in Huntsville group.

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Solar Wind Flow with Hydrogen Pickup

Cited by 19 publications

References 0 publications

Velocity oscillations in the outer heliosphere: A signature of pickup ion temperature variability?

Velocity oscillations in the outer heliosphere: A signature of pickup ion temperature variability?

Realistic and time-varying outer heliospheric modelling

Physics of the Solar Wind–Local Interstellar Medium Interaction: Role of Magnetic Fields

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