Linear Stability in the Inner Heliosphere: Helios Re-evaluated

Klein, K. G.; Martinović, M.; Stansby, David; Horbury, T. S.

doi:10.3847/1538-4357/ab5802

Cited by 25 publications

(26 citation statements)

References 48 publications

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“…For each time interval, PLUMAGE determined the fastest growing mode as well as the associated plasma response at length scales spanning k ⊥ ρ c ∈ [10 −3 , 3] and k ρ c ∈ [10 −2 , 3] (see Fig. 1 and the associated test in Klein et al (2019) for additional details on the method). Fig.…”

Section: Additional Instability Characterizationsmentioning

confidence: 99%

Parker Solar Probe Observations of Proton Beams Simultaneous with Ion-scale Waves

Verniero

Larson

Livi

et al. 2020

ApJS

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106

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Parker Solar Probe (PSP), NASA's latest and closest mission to the Sun, is on a journey to investigate fundamental enigmas of the inner heliosphere. This paper reports initial observations made by the Solar Probe Analyzer for Ions (SPAN-I), one of the instruments in the Solar Wind Electrons Alphas and Protons (SWEAP) instrument suite. We address the presence of secondary proton beams in concert with ion-scale waves observed by FIELDS, the electromagnetic fields instrument suite. We show two events from PSP's 2 nd orbit that demonstrate signatures consistent with wave-particle interactions. We showcase 3D velocity distribution functions (VDFs) measured by SPAN-I during times of strong wave power at ion-scales. From an initial instability analysis, we infer that the VDFs departed far enough away from local thermodynamic equilibrium (LTE) to provide sufficient free energy to locally generate waves. These events exemplify the types of instabilities that may be present and, as such, may guide future data analysis characterizing and distinguishing between different wave-particle interactions.

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Section: Additional Instability Characterizationsmentioning

confidence: 99%

Parker Solar Probe Observations of Proton Beams Simultaneous with Ion-scale Waves

Verniero

Larson

Livi

et al. 2020

ApJS

Self Cite

106

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“…Such a clear evolution is not observed in the slow wind, between 0.3 and 1 AU protons are less magnetized accumulating near the equipartition of kinetic and magnetic energy densities (β ≈ 1) and isotropy (T p,⊥ /T p, ≈ 1), although large departures from this condition are also observed with kind of symmetry in both (gyrotropic) directions, T p,⊥ /T p, ≷ 1 (Stansby et al, 2018). More detailed results (Stansby et al, 2018;Stansby, Horbury, and Matteini, 2019;Ďurovcová, Šafránková, and Němeček, 2019) based on core and beam analysis demonstrate that the core protons are aiming to isotropize towards larger distances, while the impression of increased parallel temperature originates from the beams that become super-Alfvénic (Klein et al, 2019).…”

Section: Introductionmentioning

confidence: 96%

Solar Wind Plasma Particles Organized by the Flow Speed

2020

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Recent reports of the first data from Parker Solar Probe (PSP) have pointed to a series of links, correlations or anti-correlations between the solar wind bulk speed ($V_{\mathrm{SW}}$ V SW ) and physical properties of plasma particles from less than 0.25 AU in the corona. In the present paper, we describe corresponding and additional links of solar wind properties, at 0.4 AU and 1.0 AU, in an attempt to complement the PSP data and understand their evolution. A detailed analysis is carried out for the main electron populations, comparing the low-energy (thermal) core and the collisionless suprathermal halo. We show that the anti-correlation observed at 0.4 AU between $V_{\mathrm{SW}}$ V SW and the number density (average value) is maintained also at 1 AU for both the core and halo electrons. On the contrary, only the core electrons manifest a clear anti-correlation of the temperature with $V_{\mathrm{SW}}$ V SW , while the halo temperature does not vary much. We also describe the ions, protons and helium, which have a more reduced mobility and their properties exhibit different variations with the solar wind speed. The results are used to shed more light on the mechanisms leading to a differential acceleration of these species and the origin of slow and fast wind modulation.

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“…7) is associated with right-handed turbulent fluctuations propagating anti-sunward, with polarisation properties consistent with KAWs (e.g., Howes & Quataert 2010;He et al 2012b). The helicity signatures σ m ±0.8 between 0.1-1 Hz are associated with small-scale kinetic instabilities driven by non-equilibrium features in the particle distribution functions (Kasper et al 2002(Kasper et al , 2008(Kasper et al , 2013Hellinger et al 2006;Matteini et al 2007;Bale et al 2009;Maruca et al 2012;Bourouaine et al 2013;Gary et al 2015;Alterman et al 2018;Klein et al 2018Klein et al , 2019.…”

Section: Magnetic Helicity Spectrogramsmentioning

confidence: 99%

First Solar Orbiter observation of the Alfvénic slow wind and identification of its solar source

D’Amicis

Bruno

Panasenco

et al. 2021

A&A

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Context. Turbulence dominated by large amplitude nonlinear Alfvén-like fluctuations mainly propagating away from the Sun is ubiquitous in high speed solar wind streams. Recent studies have shown that also slow wind streams may show strong Alfvénic signatures, especially in the inner heliosphere. Aims. The present study focuses on the characterisation of an Alfvénic slow solar wind interval observed by Solar Orbiter on July 14-18, 2020 at a heliocentric distance of 0.64 AU. Methods. Our analysis is based on plasma moments and magnetic field measurements from the Solar Wind Analyser (SWA) and Magnetometer (MAG) instruments, respectively. We compare the behaviour of different parameters to characterise the stream in terms of the Alfvénic content and magnetic properties. We perform also a spectral analysis to highlight spectral features and waves signature using power spectral density and magnetic helicity spectrograms, respectively. Moreover, we reconstruct the Solar Orbiter magnetic connectivity to the solar sources via both a ballistic and a Potential Field Source Surface (PFSS) model. Results. The Alfvénic slow wind stream described in this paper resembles in many respects a fast wind stream. Indeed, at large scales, the time series of the speed profile shows a compression region, a main portion of the stream and a rarefaction region, characterised by different features. Moreover, before the rarefaction region, we pinpoint several structures at different scales recalling the spaghetti-like flux-tube texture of the interplanetary magnetic field. Finally, we identify the connections between Solar Orbiter in situ measurements, tracing them down to coronal streamer and pseudostreamer configurations. Conclusions. The characterisation of the Alfvénic slow wind stream observed by Solar Orbiter and the identification of its solar source are extremely important aspects to understand possible future observations of the same solar wind regime, especially as solar activity is increasing toward a maximum, where a higher incidence of this solar wind regime is expected.

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Linear Stability in the Inner Heliosphere: Helios Re-evaluated

Cited by 25 publications

References 48 publications

Parker Solar Probe Observations of Proton Beams Simultaneous with Ion-scale Waves

Parker Solar Probe Observations of Proton Beams Simultaneous with Ion-scale Waves

Solar Wind Plasma Particles Organized by the Flow Speed

First Solar Orbiter observation of the Alfvénic slow wind and identification of its solar source

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