Magnetic Flux Conservation in the Heliosheath Including Solar Cycle Variations of Magnetic Field Intensity

Michael, Adam; Opher, M.; Provornikova, Elena; Richardson, J. D.; Tóth, G.

doi:10.1088/2041-8205/803/1/l6

Cited by 15 publications

(14 citation statements)

References 27 publications

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“…The inclusion of a time dependent solar wind with solar cycle variations would lead to an alternation between fast and slow solar wind at the poles, which would affect the ENA signal both in the polar regions near the termination shock and further back in the lobes. The solar cycle variations could also have an effect on the intensity of the solar magnetic field as shown in Michael et al (2015), which could have an effect on the collimation as well. Additionally, since the PUI density and temperature ratios used will directly affect the ENA flux, the particular method used to include these ratios may affect the ENA flux as well.…”

Section: Discussionmentioning

confidence: 99%

Globally Distributed Energetic Neutral Atom Maps for the “Croissant” Heliosphere

Kornbleuth

Opher

Michael

et al. 2018

ApJ

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A recent study by Opher et al. (2015) suggested the heliosphere has a "croissant" shape, where the heliosheath plasma is confined by the toroidal solar magnetic field. The "croissant" heliosphere is in contrast to the classically accepted view of a comet-like tail. We investigate the effect of the "croissant" heliosphere model on energetic neutral atom (ENA) maps. Regardless of the existence of a split tail, the confinement of the heliosheath plasma should appear in ENA maps. ENA maps from the Interstellar Boundary Explorer (IBEX) have shown two high latitude lobes with excess ENA flux at higher energies in the tail of the heliosphere. These lobes could be a signature of the confinement of the heliosheath plasma, while some have argued they are caused by the fast/slow solar wind profile. Here we present ENA maps of the "croissant" heliosphere, focusing on understanding the effect of the heliosheath plasma collimation by the solar magnetic field while using a uniform solar wind. We incorporate pick-up ions (PUIs) into our model based on Malama et al. (2006) and Zank et al. (2010). We use the neutral solution from our MHD model to determine the angular variation of the PUIs, and include the extinction of PUIs in the heliosheath. In the presence of a uniform solar wind, we find that the collimation in the "croissant" heliosphere does manifest itself into two high latitude lobes of increased ENA flux in the downwind direction.

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Section: Discussionmentioning

confidence: 99%

Globally Distributed Energetic Neutral Atom Maps for the “Croissant” Heliosphere

Kornbleuth

Opher

Michael

et al. 2018

ApJ

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“…A variety of models (e.g., Pogorelov et al 2009Pogorelov et al , 2012Pogorelov et al , 2013Opher et al 2011Opher et al , 2012Opher & Drake 2013;Washimi et al 2011;Borovikov et al 2012;Fisk & Gloeckler 2013) describe the structure and dynamics in the heliosheath. Recent models by Provornikova et al (2013Provornikova et al ( , 2014 and by Michael et al (2015) predict the observed B and radial speeds at V1 and V2. Whang & Burlaga (1994;Whang et al 1995) followed the evolution of a GMIR through the supersonic wind and heliosheath and its interaction with the heliopause.…”

Section: Structure and Formation Of The Interaction Regionmentioning

confidence: 94%

“…Pogorelov et al (2009Pogorelov et al ( , 2012 showed that the decrease in the speed to V R  0 could be explained by a nonstationary three-dimensional model that included solar cycle variations. On the other hand, Provornikova et al (2013Provornikova et al ( , 2014 and Michael et al (2015), who considered solar cycle variations in an MHD model with boundary conditions near the Sun, predicted that the speed at V1 should be a constant. They interpreted the decrease in magnetic flux at V1 as a result of magnetic reconnection.…”

Section: Magnetic Flux Conservationmentioning

confidence: 99%

Heliosheath Magnetic Field and Plasma Observed by Voyager 2 During 2012 in the Rising Phase of Solar Cycle 24

Burlaga

Ness

Richardson

et al. 2016

ApJ

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We discuss magnetic field and plasma observations of the heliosheath made by Voyager 2 (V2) during 2012, when V2 was observing the effects of increasing solar activity following the solar minimum in 2009. The average magnetic field strength B was 0.14 nT and B reached 0.29 nT on day 249. V2 was in a unipolar region in which the magnetic polarity was directed away from the Sun along the Parker spiral 88% of the time, indicating that V2 was poleward of the heliospheric current sheet throughout most of 2012. The magnetic flux at V2 during 2012 was constant. A merged interaction region (MIR) was observed, and the flow speed increased as the MIR moved past V2. The MIR caused a decrease in the >70 MeV nuc −1 cosmic-ray intensity. The increments of B can be described by a q-Gaussian distribution with q=1.2±0.1 for daily averages and q=1.82±0.03 for hour averages. Eight isolated current sheets ("PBLs") and four closely spaced pairs of current sheets were observed. The average change of B across the current sheets was a factor of ≈2, and B increased or decreased with equal probability. Magnetic holes and magnetic humps were also observed. The characteristic size of the PBLs was ≈6 R L , where R L is the Larmor radius of protons, and the characteristic sizes of the magnetic holes and humps were ≈38 R L and ≈11 R L , respectively.

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“…A number of models attempted to describe the evolution of the solar wind from 1 au, through the heliosheath, and beyond (Zank et al 1996;Baranov & Zaitsev 1998;Zank & Müller 2003;Liu et al 2007Liu et al , 2014Pogorelov et al 2012aPogorelov et al , 2013Opher et al 2011;Borovikov et al 2012;Opher 2012;Provornikova et al 2013Provornikova et al , 2014Fermo et al 2015;Michael et al 2015;Zirnstein et al 2016).…”

Section: Relationship Between the Magnetic Fields Observed In The Heliosheath And Magnetic Fields Observed In The Vlismmentioning

confidence: 99%

A Magnetic Pressure Front Upstream of the Heliopause and the Heliosheath Magnetic Fields and Plasma, Observed during 2017

Burlaga¹,

Ness

Berdichevsky

et al. 2019

ApJ

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Voyager 1 (V1), moving in the interstellar magnetic field, observed an increase in the daily averages of B beginning on day ≈346, 2016, rising to a local maximum on day ≈382, and declining nearly monotonically for the most part until day 720, measured from 2016.0. A pressure front was observed during a ≈35-day interval beginning on day 346, 2016. The pressure front observed by V1 was not a shock, although one might expect it to evolve into a shock. Voyager 2 (V2) observed the distant heliosheath during 2017. The average B in the heliosheath was relatively high, 0.130 nT. The distribution of azimuthal angles had two nearly equal maxima at approximately 90°and 180°. An unusual transition of the BT component from a large "away" sector to a large "toward" sector occurred during 2017 from day 101 to day 239. Abrupt but small changes in magnetic polarity occurred between day 146 and day 239, when the average BT component of B was close to zero. Changes in the >70 MeV nucleon −1 cosmic-ray intensity were qualitatively related to the B(t) profile described by the CR-B relationship. There was no net decrease in magnetic flux at V2 in the heliosheath during 2017 that might be attributed to ongoing magnetic reconnection in the heliosheath. Small-scale increments in B can be described by a q-Gaussian distribution with q=1.64±0.02 for hourly averages of B and q=1.54±0.08 for daily averages of B.

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Magnetic Flux Conservation in the Heliosheath Including Solar Cycle Variations of Magnetic Field Intensity

Cited by 15 publications

References 27 publications

Globally Distributed Energetic Neutral Atom Maps for the “Croissant” Heliosphere

Globally Distributed Energetic Neutral Atom Maps for the “Croissant” Heliosphere

Heliosheath Magnetic Field and Plasma Observed by Voyager 2 During 2012 in the Rising Phase of Solar Cycle 24

A Magnetic Pressure Front Upstream of the Heliopause and the Heliosheath Magnetic Fields and Plasma, Observed during 2017

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