Voyager observations of magnetic fields and cosmic rays in the heliosheath

Burlaga, L. F.; Ness, N. F.; Stone, E. C.; McDonald, F. B.

doi:10.1029/2011ja016914

Cited by 19 publications

(22 citation statements)

References 30 publications

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“…The effects of a termination shock or heliosheath are not included in the present study. This is a limitation, in that observations and numerical simulations have shown that some modulation can occur within the heliosheath (see, e.g., Caballero-Lopez et al 2010;Burlaga et al 2011). The exclusion of effects due to the heliosheath is done for two reasons (Engelbrecht & Burger 2013), the first of which is that the Oughton et al (2011) was derived assuming an Alfvén speed considerably smaller than the solar wind speed, which is not the case in the heliosheath.…”

Section: Cosmic-ray Modulationmentioning

confidence: 99%

An Ab Initio Model for the Modulation of Galactic Cosmic-Ray Electrons

Engelbrecht

Burger

2013

ApJ

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The modulation of galactic cosmic-ray electrons is studied using an ab initio three-dimensional steady state cosmicray modulation code in which the effects of turbulence on both the diffusion and drift of these cosmic-rays are treated as self-consistently as possible. A significant refinement is that a recent two-component turbulence transport model is used. This model yields results in reasonable agreement with observations of turbulence quantities throughout the heliosphere. The sensitivity of computed galactic electron intensities to choices of various turbulence parameters pertaining to the dissipation range of the slab turbulence spectrum, and to the choice of model of dynamical turbulence, is demonstrated using diffusion coefficients derived from the quasi-linear and extended nonlinear guiding center theories. Computed electron intensities and latitude gradients are also compared with spacecraft observations.

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Section: Cosmic-ray Modulationmentioning

confidence: 99%

An Ab Initio Model for the Modulation of Galactic Cosmic-Ray Electrons

Engelbrecht

Burger

2013

ApJ

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“…The widths of all these current sheets, assumed to be nonpropagating, correspond to thicknesses of the order of 15-30 R L , similar to vales in the supersonic solar wind. Here R L , is the Larmor radius of the pickup ion dominated plasma in the heliosheath, where the characteristic temperature is 4.6 × 10 6 K and the average B is ≈ 0.1 nT [23].…”

Section: Discussionmentioning

confidence: 99%

Current sheets in the heliosheath: Voyager 1, 2009

Burlaga¹,

Ness²

2012

AIP Conference Proceedings

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Models of the infinitely thin global heliospheric current sheet AIP Conf. Proc. 1216, 371 (2010); 10.1063/1.3395878 Foreshock, termination shock, and heliosheath: Voyager 1/2 observations of structure and turbulence AIP Conf.Abstract. Current sheets were observed by Voyager 1 (V1) from DOY 1 to 331, 2009, in the heliosheath between 108.5 and 111.8 AU. We discuss observations of a proton boundary layer ("PBL"), a magnetic hole, a magnetic hump, and a current sheet associated with a sector boundary. The magnetic field strength changed across the PBL, the magnetic hole and the magnetic hump, but the direction of B did not change across these structures. At sector boundaries, B rotated in a plane normal to the minimum variance direction, and the component of B along the minimum variance direction was zero within the uncertainties, indicating that the sector boundary was a tangential discontinuity. The widths (passage times) of these current sheets, assumed to be non-propagating, ranged from 1.6 to 4.4 hours, corresponding to thicknesses of the order of 15 -30 R L .

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“…A GMIR in the supersonic solar wind can be preceded by a strong shock, which results from the coalescence of many forward shocks produced by solar activity [Burlaga et al 2003]. An example of a GMIR produced in the heliosheath observed by V2 is shown in Figure 4 [Burlaga et al 2011] In this case, the magnetic field strength in the GMIR is twice that in the ambient heliosheath, and it moved past V2 during an interval of 40 days. There is an indication that the GMIR was preceded by a fast-forward shock, but this occurred in a data gao.…”

Section: Heliosheathmentioning

confidence: 99%

“…Such a cosmic ray profile is called a long-lasting Forbush decrease. The red curve and Figure 4b is derived from the CR-B relation [Burlaga et al 2011] that has been observed in the heliosphere that distances greater than or equal to 10 AU. Burlaga et al [1993] found that long-lasting Forbush decreases were associated with sustained enhanced solar activity for 1-3 solar rotations which introduce strong fields carried by coronal mass ejection and magnetic clouds as well as shocks associated with faster streams associated with these ejecta Burlaga et al [2003] showed that such activity could produce organized structures (expanding shells of disturbed magnetic fields and shocks) in the heliosphere at approximately 15 AU characterized by an interval of strong magnetic fields moving past V1 and V2 for 1-3 solar rotations, and persisting out to at least 90 AU.…”

Section: Heliosheathmentioning

confidence: 99%

Voyager observations of the magnetic field in the heliosheath and the local interstellar medium

Burlaga

2015

J. Phys.: Conf. Ser.

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Abstract. This paper reviews observations of the magnetic field B in the heliosheath by Voyager 1 (V1) and Voyager 2 (V2) and the recent observations of the LISM by V1. The heliosheath is the region between the termination shock (TS) and the heliopause (HP). The TS was identified by both V1 and V2, and the internal structure of the TS was determined by V2. The radial distance of the TS was 94 AU at V1 and 84 AU at V2, suggesting a global asymmetry of the heliosphere. The average direction of B in the heliosheath is that of the Parker spiral magnetic field, and non-periodic magnetic sectors were observed by V1 and V2. The heliosheath is disturbed and turbulent, particularly just behind the TS, and it is described by the multifractal spectrum, the q-correlation function and the q-Gaussian distribution. The multifractal spectrum in the heliosheath also varies with the solar cycle. Voyager 1 has been in the LISM since at least August 25, 2012, but the nature of the HP and the time of the HP crossing not been determined. The magnetic field direction is close to, but distinguishable from the Parker spiral magnetic field, and its departure from the Parker spiral magnetic field is slowly increasing with distance from the sun. A large pressure pulse and two shocks or pressure waves have been identified in the LISM, presumably generated inside the heliosphere and transmitted through the heliosheath and heliopause. The interstellar magnetic field lines are draped across the heliopause, and B is approximately 0.5 nT . The fluctuations of B are very small but turbulent on scales 1 day to 468 days, with a Kolmogorov spectrum and an injection scale of approximately 10 pc. IntroductionThis paper discusses the magnetic field observations of the heliosheath observed by Voyager 1 (V1) and Voyager 2 (V2) and the recent observations of the interstellar magnetic fields originating in the local interstellar medium (LISM). Earlier reviews of the heliosheath and its interaction with the LISM were published by Seuss [1990], Axford [1990] and Zank [1999]. A recent comprehensive discussion of this topic is given by Zank [2015].Voyager 1 is currently observing interstellar magnetic fields that are disturbed by the interaction between the heliosphere and the LISM in a region that may extend tens of AU beyond the current position of V1. Although the term LISM is used in many of the papers discussing observations and corresponding theories of the interstellar magnetic fields observed by V1, it is becoming

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Voyager observations of magnetic fields and cosmic rays in the heliosheath

Cited by 19 publications

References 30 publications

An Ab Initio Model for the Modulation of Galactic Cosmic-Ray Electrons

An Ab Initio Model for the Modulation of Galactic Cosmic-Ray Electrons

Current sheets in the heliosheath: Voyager 1, 2009

Voyager observations of the magnetic field in the heliosheath and the local interstellar medium

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