The Early History of Heliospheric Science and the Spacecraft That Made It Possible

Zank, G. P.; Sterken, Veerle; Giacalone, J.; Möbius, E.; Steiger, R. von; Stone, E. S.; Krimigis, S. M.; Richardson, J. D.; Linsky, Jeffrey L.; Izmodenov, V.; Heber, B.

doi:10.1007/s11214-022-00900-8

Cited by 9 publications

(7 citation statements)

References 197 publications

(359 reference statements)

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“…The models of the heliospheric magnetic fields in the solar wind were widely discussed (see e.g. Axford 1972;Zank et al 2022, and the references therein) and see Herbst et al (2022) for a recent review of models of stellar astrospheres. In particular, it was shown by Axford (1972) and Cranfill (1974) that in nearly incompressible subsonic flow downstream of the spherical wind termination shock the azimuthal magnetic field 𝐵 𝜙 would increase as ∝ 𝑟 up to the magnitude which is dynamically significant to affect the plasma flow.…”

Section: Magnetic Field Amplification In the Cluster Corementioning

confidence: 99%

Inside the core of a young massive star cluster: 3D MHD simulations

Badmaev

Bykov

Kalyashova

2022

Monthly Notices of the Royal Astronomical Society

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Young massive star clusters inhabit regions of star formation and play an essential role in the galactic evolution. They are sources of both thermal and non-thermal radiation, and they are effective cosmic ray accelerators. We present the 3D magnetohydrodynamic (MHD) modeling of the plasma flows in a young compact cluster at the evolutionary stage comprising multiple interacting supersonic winds of massive OB and WR stars. The modeling allows studying the partitioning of the mechanical energy injected by the winds between the bulk motions, thermal heating and magnetic fields. Cluster-scale magnetic fields reaching the magnitudes of ∼ 300 μG show the filamentary structures spreading throughout the cluster core. The filaments with the high magnetic fields are produced by the Axford-Cranfill type effect in the downstream of the wind termination shocks, which is amplified by a compression of the fields with the hot plasma thermal pressure in the central part of the cluster core. The hot (∼ a few keV) plasma is heated at the termination shocks of the stellar winds and compressed in the colliding postshock flows. We also discuss a possible role of the thermal conduction effects on the plasma flow, analyse temperature maps in the cluster core and the diffuse thermal X-ray emission spectra. The presence of high cluster-scale magnetic fields supports the possibility of high-energy cosmic ray acceleration in clusters at the given evolutionary stage.

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Section: Magnetic Field Amplification In the Cluster Corementioning

confidence: 99%

Inside the core of a young massive star cluster: 3D MHD simulations

Badmaev

Bykov

Kalyashova

2022

Monthly Notices of the Royal Astronomical Society

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“…[15], but a proper treatment of the Spreiter number would permit this to be tightened, while keeping in mind that there are several additional factors that modify ram pressure stripping such as the effects of extended gas [17,18]. Thirdly, there are important astronomical applications for which the Mach number is close to unity, including shocks in the very local interstellar medium (VLISM) [19,20], in which case momentum flux overestimates ram pressure by false(1−Spfalse)/Sp≈50normal% (figure 4).…”

Section: Discussionmentioning

confidence: 99%

Ram pressure in astronomy and engineering

Dowling

Bradley

2023

Proc. R. Soc. A.

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The ram pressure of a moving fluid, P r , is the rise in pressure at a stagnation point relative to the upstream pressure. In astronomy, it is used to calculate the interaction of stellar winds with planets and to quantify the effects of ram pressure stripping. On aeroplanes and in wind tunnels, it is measured with a pitot-static tube, an inexpensive device with no moving parts that was invented in 1732. Up through the mid-1960s, across both astronomy and engineering the ram pressure of a moving gas and its momentum flux, ρ u 2 , where ρ and u are the upstream mass density and flow speed, were properly treated as related but distinct quantities. This relationship may be expressed as P r = Sp ρ u 2 , where Sp is the dimensionless Spreiter number, which ranges between 0.5 and 0.88 for a monatomic gas, depending on the upstream Mach number, Ma . Unfortunately, by the early 1970s, in astronomy ram pressure was defined to be the momentum flux and Sp was fixed to be unity and forgotten as a parameter. This article seeks to raise awareness of this issue, and to review the determination of Sp for subsonic and supersonic flow.

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“…H atoms resonantly scatter Lyman‐α photons. IPH properties have therefore been examined using Lyman‐α emissions observed by multiple spacecraft from various points in the solar system (e.g., Baliukin et al., 2022; Galli et al., 2022; Zank et al., 2022) It is found that the IPH flow direction emanates from close to the heliospheric “nose” with no significant variation of the IPH flow longitude over time (Lallement et al., 2005; Koutroumpa et al., 2017). The IPH velocity ranges between 18 ± 2 km/s and 25.7 ± 2 km/s, and varies with solar activity, line of sight, and distance from the Sun (Vincent et al., 2011).…”

Section: Introductionmentioning

confidence: 99%