A strong, highly-tilted interstellar magnetic field near the Solar System

Opher, M.; Bibi, F. Alouani; Tóth, G.; Richardson, J. D.; Izmodenov, Vladislav; Gombosi, T. I.

doi:10.1038/nature08567

Cited by 137 publications

(164 citation statements)

References 23 publications

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“…The model of the interstellar field used in our calculations was found to be able to explain this difference in the framework of the stationary model of the heliosphere . It is also close to the results of Opher et al (2009) The recent energetic neutral atoms observations by IBEX found a ribbon structure of enhanced emission, thought to be caused by the interstellar magnetic field and reflecting its orientation. Heerikhuisen et al (2010) reproduce the ribbon structure seen in the IBEX data using the field (parallel to the hydrogen deflection plane) of strength 3 μG directed towards (224 • , 41 • ) which is (apart from the overall sign change) within about 20 • from our direction.…”

Section: Discussionsupporting

confidence: 71%

Structure of the heliospheric current sheet from plasma convection in time-dependent heliospheric models

Czechowski¹,

Strumik²,

Grygorczuk³

et al. 2010

A&A

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Context. The heliospheric current sheet is a plasma layer dividing the heliosphere into the regions of different magnetic field polarity. Since it is very thin compared to the size of the system, it is difficult to incorporate into the numerical models of the heliosphere. Because of the solar magnetic field reversals and the diverging and slowing down plasma flow in the outer heliosphere, the heliospheric current sheet is expected to have a complicated structure, with important consequences for transport processes in the heliosheath. Aims. We determine the shape and time evolution of the current sheet in selected time-dependent 3-D models of the heliosphere, assuming that the heliospheric current sheet is a tangential discontinuity convected by the plasma flow. Methods. We have derived the shape of the heliospheric current sheet at a given time by following the plasma flow lines originating at the neutral line on the source surface surrounding the Sun. The plasma flow was obtained from numerical MHD or gas-dynamical solutions.Results. The large-scale structure of the magnetic field polarity regions and the heliospheric current sheet in time-dependent asymmetric models of the heliosphere differs from the results obtained in simpler models. In particular, in the forward heliosheath it is characterized by secondary folds in the heliospheric current sheet that are caused by the solar wind latitudinal variation over the solar cycle. We present examples illustrating some cases of interest: a "bent" current sheet, and the HCS structure during the magnetic field reversal at the solar maximum. We also discuss the evolution of the magnetic polarity structure in the region close to the heliopause.

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Section: Discussionsupporting

confidence: 71%

Structure of the heliospheric current sheet from plasma convection in time-dependent heliospheric models

Czechowski¹,

Strumik²,

Grygorczuk³

et al. 2010

A&A

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“…its large scale component has a tendency to be aligned with the galactic spiral arms (Gaensler 1998). If the strength of the ISM magnetic field can reach up to several tenths of Gauss in the center of our Galaxy (see Rand & Kulkarni 1989;Ohno & Shibata 1993;Opher et al 2009;Shabala et al 2010), it can be even stronger in the cold phase of the ISM (Crutcher et al 1999). In particular, radio polarization measures of the magnetic field in the context of Galactic ionized supershells are reported to be 2-6 µG in Harvey-Smith et al (2011).…”

Section: Introductionmentioning

confidence: 99%

Bow shock nebulae of hot massive stars in a magnetized medium

Meyer

Mignone

Kuiper

et al. 2016

Mon. Not. R. Astron. Soc.

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A significant fraction of OB-type, main-sequence massive stars are classified as runaway and move supersonically through the interstellar medium (ISM). Their strong stellar winds interact with their surroundings where the typical strength of the local ISM magnetic field is about 3.5-7 µG, which can result in the formation of bow shock nebulae. We investigate the effects of such magnetic fields, aligned with the motion of the flow, on the formation and emission properties of these circumstellar structures. Our axisymmetric, magneto-hydrodynamical simulations with optically-thin radiative cooling, heating and anisotropic thermal conduction show that the presence of the background ISM magnetic field affects the projected optical emission our bow shocks at Hα and [OIII] λ 5007 which become fainter by about 1-2 orders of magnitude, respectively. Radiative transfer calculations against dust opacity indicate that the magnetic field slightly diminishes their projected infrared emission and that our bow shocks emit brightly at 60 µm. This may explain why the bow shocks generated by ionizing runaway massive stars are often difficult to identify. Finally, we discuss our results in the context of the bow shock of ζ Ophiuchi and we support the interpretation of its imperfect morphology as an evidence of the presence of an ISM magnetic field not aligned with the motion of its driving star.

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“…Most global models of the outer heliosphere treat the ion components of the solar wind as a single MHD fluid [Opher et al, 2006[Opher et al, , 2009Pogorelov et al, 2007;Alouani-Bibi et al, 2011;Ratkiewicz and Grygorczuk, 2008;Izmodenov et al, 2009]. These models do not yield a self-consistent description of the pickup ions; therefore, additional assumptions are needed to link the upstream pickup ion pressure with the downstream pickup ion pressure across the termination shock [Zank et al, 1996[Zank et al, , 2010Fahr and Chalov, 2008].…”

Section: Introductionmentioning

confidence: 99%

Constraining the pickup ion abundance and temperature through the multifluid reconstruction of the Voyager 2 termination shock crossing

et al. 2015

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Voyager 2 observations revealed that the hot solar wind ions (the so‐called pickup ions) play a dominant role in the thermodynamics of the termination shock and the heliosheath. The number density and temperature of this hot population, however, have remained unknown, since the plasma instrument on board Voyager 2 can only detect the colder thermal ion component. Here we show that due to the multifluid nature of the plasma, the fast magnetosonic mode splits into a low‐frequency fast mode and a high‐frequency fast mode. The coupling between the two fast modes results in a quasi‐stationary nonlinear wave mode, the “oscilliton,” which creates a large‐amplitude trailing wave train downstream of the thermal ion shock. By fitting multifluid shock wave solutions to the shock structure observed by Voyager 2, we are able to constrain both the abundance and the temperature of the undetected pickup ions. In our three‐fluid model, we take into account the nonnegligible partial pressure of suprathermal energetic electrons (0.022–1.5 MeV) observed by the Low‐Energy Charged Particle Experiment instrument on board Voyager 2. The best fitting simulation suggests a pickup ion abundance of 20 ± 3%, an upstream pickup ion temperature of 13.4 ± 2 MK, and a hot electron population with an apparent temperature of ~0.83 MK. We conclude that the actual shock transition is a subcritical dispersive shock wave with low Mach number and high plasma β.

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A strong, highly-tilted interstellar magnetic field near the Solar System

Cited by 137 publications

References 23 publications

Structure of the heliospheric current sheet from plasma convection in time-dependent heliospheric models

Structure of the heliospheric current sheet from plasma convection in time-dependent heliospheric models

Bow shock nebulae of hot massive stars in a magnetized medium

Constraining the pickup ion abundance and temperature through the multifluid reconstruction of the Voyager 2 termination shock crossing

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