Solar cycle and latitude dependence of high-beta suprathermal plasma conditions in interplanetary space between 1.3 and 5.4AU

Marhavilas, P. K.

doi:10.1016/j.asr.2012.02.011

Cited by 4 publications

(1 citation statement)

References 15 publications

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“…Such periods were associated with energetic particle intensity enhancements associated with the passage of shocks driven by coronal mass ejections (CMEs) or corotating interaction regions (CIRs) as well as with intervals of prominent magnetic depressions (cf. Kasotakis et al 1999;Marhavilas 2012). In this paper we study how common the periods with P EP exceeding P B are at heliocentric distances R∼1 AU.…”

Section: Introductionmentioning

confidence: 99%

Energetic Particle Pressure at Interplanetary Shocks: STEREO-A Observations

Lario,

Decker,

Roelof

et al. 2015

Preprint

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We study periods of elevated energetic particle intensities observed by STEREO-A when the partial pressure exerted by energetic (≥83 keV) protons (P EP ) is larger than the pressure exerted by the interplanetary magnetic field (P B ). In the majority of cases, these periods are associated with the passage of interplanetary shocks. Periods when P EP exceeds P B by more than one order of magnitude are observed in the upstream region of fast interplanetary shocks where depressed magnetic field regions coincide with increases of the energetic particle intensities. When solar wind parameters are available, P EP also exceeds the pressure exerted by the solar wind thermal population (P T H ). Prolonged periods (>12 h) with both P EP >P B and P EP >P T H may also occur when energetic particles accelerated by an approaching shock encounter a region well-upstream of the shock characterized by low magnetic field magnitude and tenuous solar wind density. Quasi-exponential increases of the sum P SU M =P B +P T H +P EP are observed in the immediate upstream region of the shocks regardless of individual changes in P EP , P B and P T H , indicating a coupling between P EP and the pressure of the background medium characterized by P B and P T H . The quasi-exponential increase of P SU M implies a convected exponential radial gradient ∂P SU M /∂r>0 that results in an outward force applied to the plasma upstream of the shock. This force can be maintained by the mobile energetic particles streaming upstream of the shocks that, in the most intense events, drive electric currents able to generate diamagnetic cavities and depressed solar wind density regions.

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Section: Introductionmentioning

confidence: 99%