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REVIEW 3 major objections 4 minor 65 references

Solar wind protons are heated perpendicular to the magnetic field from 0.05 to 1 au, and this heating substantially slows the growth of temperature anisotropy predicted by double-adiabatic expansion.

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2026-08-01 01:21 UTC pith:JB2PZHPB

load-bearing objection Useful consolidation of perpendicular proton heating with new quantitative radial profiles; core claim holds, but rates need uncertainty and heat-flux caveats. the 3 major comments →

arxiv 2607.25824 v1 pith:JB2PZHPB submitted 2026-07-28 astro-ph.SR

Solar Wind Proton Heating and its Effect on Temperature Anisotropy Evolution between 0.05 and 1 au

Etienne Berriot , Arnaud Zaslavsky , Olga Alexandrova , Pascal D\'emoulin , Petr Hellinger , Lorenzo Matteini This is my paper
classification astro-ph.SR
keywords solarwindheatingevolutiontemperatureadiabaticanisotropiesanisotropy
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved

The pith

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

This paper tries to establish that, across the entire inner heliosphere sampled by Parker Solar Probe and Solar Orbiter, solar wind protons receive non-adiabatic heating in the direction perpendicular to the local magnetic field, while the parallel direction behaves adiabatically. The perpendicular heating is strong enough to significantly reduce the temperature anisotropy that would develop if the plasma expanded double-adiabatically. Despite this heating, slower wind streams still develop a parallel-dominated anisotropy that becomes constrained by kinetic firehose instabilities. If correct, the solar wind is not double-adiabatic even close to the Sun, and perpendicular energy input is a major control on the plasma's stability evolution.

Core claim

By monitoring the radial evolution of the two Chew-Goldberger-Low adiabatic invariants, C_∥ = T_∥(B/n)² and C_⊥ = T_⊥/B, in Parker Solar Probe (0.05–0.25 au) and Solar Orbiter (0.3–1 au) data, the paper finds that C_⊥ increases with distance for both slow and fast solar wind, definitively indicating non-adiabatic perpendicular proton heating. C_∥, by contrast, shows no clear deviation from a constant value, indicating no average parallel heating or cooling. The perpendicular heating rates are higher in the faster wind and decrease with distance, but across all distances the heating is sufficient to make the observed decrease of T_⊥/T_∥ slower than the double-adiabatic prediction. Consequentl

What carries the argument

The central objects are the two adiabatic invariants C_∥ = T_∥(B/n)² and C_⊥ = T_⊥/B, whose log-time derivatives equal the non-adiabatic heating rates normalized by pressure: (1/2)d/dt ln C_∥ = Q_∥/P_∥ and d/dt ln C_⊥ = Q_⊥/P_⊥. Under the double-adiabatic (CGL) approximation these invariants are exactly conserved; any measured secular change in them with heliocentric distance directly signals non-adiabatic heating or cooling. The paper exploits this by converting the radial sequence of binned spacecraft measurements into a temporal derivative via d/dt = u_R d/dR, allowing it to quantify the heating rates from the observed slopes of ln C_∥ and ln C_⊥.

Load-bearing premise

The identification of the observed increase in C_⊥ with distance as 'heating' assumes that the binned radial sequence of measurements represents the Lagrangian evolution of the same plasma population (d/dt = u_R d/dR), and that neglected heat-flux and non-gyrotropic pressure terms are small—an assumption that is stated but not demonstrated.

What would settle it

A measurement that follows the same plasma parcel or streams as they move outward (for instance, using a radial-aligned pair of spacecraft, or tracking features in the distribution function) that shows C_⊥ not increasing with distance would refute the claim of genuine perpendicular heating. Alternatively, a full evaluation of the heat-flux term in the C_⊥ evolution equation that shows it accounts for most of the observed dC_⊥/dR would falsify the attribution to heating.

Watch this falsifier. Get emailed when new claim-graph text bears on it.

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If this is right

  • If the perpendicular heating is real, then standard double-adiabatic (CGL) models of the inner heliosphere are inadequate even close to the Sun; models must include a perpendicular energy source.
  • The reduced rate of anisotropy growth means the onset of firehose and other kinetic instabilities is delayed or weakened relative to adiabatic predictions, changing where in the solar wind unstable conditions first appear.
  • Because the heating rates are higher in fast wind than slow wind (by a factor of ~5 in specific heating rate), the mechanism responsible likely scales with wind speed or turbulence amplitude.
  • The observed heating rate near 0.05 au (~10⁵ J s⁻¹ kg⁻¹) matches independent estimates of turbulent energy dissipation, suggesting that turbulence is a viable and possibly dominant heating source at these distances.

Where Pith is reading between the lines

These are editorial extensions of the paper, not claims the author makes directly.

  • The paper's finding that T_⊥/T_∥ ≳ 1 for both wind populations inside 0.075 au, extrapolated sunward, implies that the high corona likely also has T_⊥ > T_∥; this is a testable constraint for coronal heating models, though it rests on the same radial-sequence assumption.
  • The authors leave open the physical mechanism; a natural testable extension is to sort the same data by Alfvénicity (as they suggest) to see whether the perpendicular heating is concentrated in Alfvénic slow wind, which would link the heating to switchbacks or coherent turbulent structures.
  • The jump in C_⊥ and heating rates between PSP and SolO data near 0.3 au is attributed to calibration; if a cross-calibration or a better-aligned radial dataset were available, the true radial profile of C_⊥ might be smoother, and the inferred total heating rate could be revised.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit.

Referee Report

3 major / 4 minor

Summary. The manuscript combines Parker Solar Probe (0.05–0.25 au) and Solar Orbiter (0.3–1 au) proton moments to study the radial evolution of the two CGL adiabatic invariants C_parallel = T_parallel (B/n)^2 and C_perp = T_perp/B (Eq. 1). Splitting the data into fast and slow wind using 3–33% speed percentiles per radial bin, the authors report that ln C_parallel is approximately constant with distance while ln C_perp increases for both populations (Fig. 1). Interpreting this increase through d/dt = u_R d/dR and Eq. (3), they convert the radial slope into perpendicular heating-rate densities Q_perp and per-mass rates epsilon_perp (Fig. 2), finding rates that decrease with distance and are larger in the fast wind. They then argue that this perpendicular heating slows the double-adiabatic decrease of T_perp/T_parallel and shapes the plasma distribution in the beta_parallel–T_perp/T_parallel plane, with the slow wind approaching the firehose thresholds and the fast wind staying near the proton-cyclotron/mirror conditions (Figs. 3–5). The central claim is that solar-wind protons experience significant perpendicular heating throughout 0.05–1 au while remaining adiabatic in the parallel direction.

Significance. If the heating attribution is correct, the paper extends evidence for non-double-adiabatic proton behavior to 0.05 au, bridges PSP and Solar Orbiter observations, and provides quantitative heating rates that can be compared with turbulent dissipation estimates. The main strengths are the large multi-spacecraft dataset, the explicit percentile-based population separation that accounts for wind acceleration, and the use of two fitting forms to show that the qualitative rise of ln C_perp and flatness of ln C_parallel are robust. The paper is important, but the central inference depends on assumptions that are not demonstrated: the neglected heat-flux, non-gyrotropic, and population-mixing effects, and the quantitative rates lack a statistical uncertainty budget and are affected by a large PSP/SolO offset. These issues are addressable and do not, in my view, invalidate the qualitative result, but they are load-bearing for the abstract's 'significant average heating' statement and for the comparison with turbulence rates.

major comments (3)
  1. [Appendix A / Eq. (A.12); Section 3, Fig. 2] The central inference equates u_R d ln C_perp/dR with Q_perp/P_perp and then calls Q_perp a 'perpendicular heating rate.' But the text states that Q_perp includes heat-flux divergence, non-ideal electric fields, and non-gyrotropic pressure-tensor contributions. Equation (A.10) explicitly contains (1/2 ∇·q):bb and Tr(P_ng·∇u + ...), and none of these terms is estimated or bounded in the manuscript. If, for example, the heat-flux divergence is a non-negligible fraction of the advective term, the inferred 'heating' is not local energy dissipation. Since both PSP and SolO measure full 3D distribution functions, the authors should provide at least order-of-magnitude estimates of the heat-flux and agyrotropy terms, or alternatively use a more cautious term such as 'effective non-adiabatic rate' and avoid the direct comparison with turbulent dissipation in Section 5 until the neglected terms ar
  2. [Section 3 / Appendix B] The reduction d/dt = u_R ∂_R treats the radial sequence of binned measurements as a Lagrangian time derivative along a single steady flow. The data are not Lagrangian: PSP and SolO sample different plasma parcels at different times, and Appendix B shows that the selected wind populations accelerate by about 150–200 km/s between 0.05 and 1 au. The 3–33% percentile split is applied independently to each radial bin, so it does not track the same parcel; a radial change in the source mix within the slow/fast categories could produce a rise in ln C_perp without any heating. This is load-bearing because Eq. (3) is only valid if the same population is followed and if the non-advective terms are negligible. The authors should test for population-mixing effects (e.g., identify and track individual stream intervals, back-map plasma parcels, or compare with a constant-speed-threshold split) or soft
  3. [Section 3 / Fig. 2] The quantitative heating rates carry no statistical uncertainties. The linear and power-law fits are applied to binned means without reporting confidence intervals, goodness-of-fit, or sensitivity to the chosen bin size. More importantly, the PSP- and SolO-based rates differ by a factor of about 5–10 in epsilon_perp at R ≈ 0.25–0.3 au, and the text attributes this to calibration without quantification. As a result, the combined radial trend quoted in Section 5 (epsilon from about 10^5 to 5×10^3 J s^-1 kg^-1) is not established at a stated precision. The authors should propagate fit uncertainties and either calibrate the PSP/SolO offset using the overlap or present the two spacecraft's rates separately rather than as one continuous trend. This is needed before the rates can be compared quantitatively with turbulent dissipation estimates.
minor comments (4)
  1. [Section 2] The sentence stating SolO data are taken at 'R ∈ [0.05, 0.25] au' appears to be a typo; the rest of the paper consistently uses R ∈ [0.3, 1] au for SolO. Please correct.
  2. [Section 2] In the sentence 'both C_p⊥ and C_p⊥∥ are conserved', the second symbol should be C_p∥, not C_p⊥∥.
  3. [Table 1] The adiabatic CGL curves in Figs. 3–5 are computed from power-law exponents s(B) and s(n) fitted to the same dataset. The table note already cautions about interpretation, but the main text should state explicitly that these are data-derived baselines, not independent theoretical predictions, so that readers do not mistake the comparison for a test of double-adiabatic theory against an external model.
  4. [Section 4 / Figs. 4–5] The marginal-stability curves depend on the assumptions of bi-Maxwellian protons, beta_e = 1, and gamma = 10^-3 Omega_ci. The text mentions some limitations, but the figures would benefit from a sentence in the captions reiterating that the thresholds are not exact boundaries for the observed non-Maxwellian distributions.

Circularity Check

0 steps flagged

No significant circularity: the perpendicular-heating claim is a direct measurement of CGL invariant growth, with the heating rate defined by, not predicting, the same measured invariant.

full rationale

The derivation chain is self-contained and does not reduce to its inputs by construction. Equations (2)-(3) and (A.11)-(A.12) define Q⊥/P⊥ = d ln C⊥/dt; the central observational claim is the measured radial increase of ln C⊥ (Fig. 1b), which is a direct data product, not a fitted prediction. The heating rates in Fig. 2 are explicitly computed from fits to the measured C⊥ profile via Eq. (3), i.e. they are estimates of the defined residual, not predictions of the same data under another name. The double-adiabatic baselines in Figs. 3-5 are built from power-law exponents of B and n fitted on the same dataset (Table 1); the paper itself flags this as 'only here to provide an indicative comparison' and warns that these exponents 'should not be used to derive any other quantities, such as heating rates' (Table 1 note). This limits the strength of the graphical comparison but is not a circular reduction: the perpendicular-heating conclusion rests on the invariant growth itself, not on those baselines. Self-citations (Zaslavsky 2023; Hellinger et al. 2006) are prior observational support and standard instability thresholds, while the governing equations are re-derived in Appendix A from Hunana et al. (2019); no load-bearing step is imported solely from the authors' own prior work. Assumptions such as d/dt = u_p,R d/dR and the neglect of heat-flux/non-gyrotropic terms are physical modeling assumptions that affect interpretation, but they do not make the output equivalent to the input by construction. No specific Eq.-to-Eq. or fitted-parameter-to-prediction reduction can be exhibited.

Axiom & Free-Parameter Ledger

4 free parameters · 5 axioms · 0 invented entities

The central analysis relies on standard plasma-moment equations and on explicit modeling choices (radial-proxy assumption, instrument density proxy, instability thresholds). No new free physical entities are introduced; the listed free parameters are analysis choices and fitted baselines that determine the quantitative heating rates and anisotropy comparisons.

free parameters (4)
  • Power-law exponents s(B), s(n) per spacecraft and wind class = e.g., PSP slow: s(B)=-1.9, s(n)=-2.2; SolO slow: s(B)=-1.7, s(n)=-2.1 (Table 1)
    Fitted to binned PSP/SolO magnetic field and density data; used to construct the double-adiabatic CGL baselines in Figs. 3-5. Their uncertainty is not propagated into the comparison.
  • Linear/power-law fit slopes of ln C_perp vs R = Not tabulated explicitly; implied by Fig. 2 heating rates
    The heating rates Q_perp and epsilon_perp are computed from the derivative of these fits, so the fitted slopes determine the central quantitative claim.
  • Wind population percentile thresholds (3% and 33%) = 3% to 33% of speed distribution per radial bin
    Chosen to remove outliers and separate slow/fast wind; classification is relative to each radial bin rather than a fixed physical stream.
  • Radial bin sizes = 1e-2 au (PSP), 2e-2 au (SolO)
    Choice affects the fitted radial gradients and the scatter in the binned averages.
axioms (5)
  • standard math The proton pressure tensor evolution equations (A.7)-(A.8) and the reduction to C_perp/C_par conservation under double-adiabatic assumptions
    Standard kinetic plasma theory from Hunana et al. (2019); used to define the adiabatic invariants and heating rates.
  • domain assumption Ideal Ohm's law E = -u x B and gyrotropic pressure with zero heat flux define the adiabatic baseline
    Invoked in Section 2 and Appendix A to identify C_perp conservation as the null hypothesis; real solar wind may violate these conditions.
  • domain assumption Single-spacecraft radial binning is a valid proxy for Lagrangian evolution: d/dt = u_p,R d/dR assuming stationary, spherically expanding, radially constant-speed flow
    Stated in Section 3; the wind accelerates with distance (Appendix B), and different radial bins sample different plasma parcels, so the measured C_perp(R) is not strictly the same parcel's evolution.
  • domain assumption The marginal stability thresholds of Hellinger et al. (2006) (gamma = 1e-3 Omega_ci, bi-Maxwellian protons, beta_e=1) can be used to assess whether the observed distribution is constrained by instabilities
    Used in Figures 4-5 to identify firehose/cyclotron/mirror constraints; known idealized assumptions, acknowledged by the authors.
  • domain assumption Proton density from PSP is set equal to electron density from QTN spectroscopy
    Section 2: proton densities are taken as QTN electron densities for robustness; assumes charge neutrality and no significant alpha/electron-proton density ratio variation.

pith-pipeline@v1.3.0-alltime-deepseek · 15988 in / 13180 out tokens · 114294 ms · 2026-08-01T01:21:25.742998+00:00 · methodology

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Cite this review

Pith. "Pith review of Solar Wind Proton Heating and its Effect on Temperature Anisotropy Evolution between 0.05 and 1 au." pith.science (2026). https://pith.science/paper/JB2PZHPB

@misc{pith2026260725824,
  author       = {Pith},
  title        = {Pith review of: Solar Wind Proton Heating and its Effect on Temperature Anisotropy Evolution between 0.05 and 1 au},
  year         = {2026},
  howpublished = {\url{https://pith.science/paper/JB2PZHPB}},
  note         = {Machine review of arXiv:2607.25824}
}
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read the original abstract

This study focuses on the radial evolution of the solar wind proton adiabatic invariants and temperature anisotropies in the inner heliosphere. More specifically, we study in-situ measurements provided by the Parker Solar Probe, between 0.05 au and 0.25 au from the Sun, and Solar Orbiter spacecraft between 0.3 au and 1 au. Throughout the studied range of radial distances, we observe a significant average heating in the direction perpendicular to the local magnetic field for both fast and slow solar wind populations. On the other hand, there is no clear deviation from adiabaticity in the parallel direction regardless of the wind speed. The perpendicular heating is enough to significantly reduce the generation of the temperature anisotropy expected from a double adiabatic evolution. Despite the heating, an important portion of the solar wind (especially the slower wind streams) develops substantial anisotropies with higher parallel temperatures, which eventually become constrained by kinetic firehose instabilities.

Figures

Figures reproduced from arXiv: 2607.25824 by Arnaud Zaslavsky, Etienne Berriot, Lorenzo Matteini, Olga Alexandrova, Pascal D\'emoulin, Petr Hellinger.

Figure 1
Figure 1. Figure 1: Radial evolution of the proton adiabatic invariants’ log [PITH_FULL_IMAGE:figures/full_fig_p003_1.png] view at source ↗
Figure 3
Figure 3. Figure 3: Radial evolution of the solar wind proton temperature [PITH_FULL_IMAGE:figures/full_fig_p004_3.png] view at source ↗
Figure 2
Figure 2. Figure 2: Perpendicular non-adiabatic proton heating rate density [PITH_FULL_IMAGE:figures/full_fig_p004_2.png] view at source ↗
Figure 4
Figure 4. Figure 4: Evolution of the solar wind plasma distribution in the [PITH_FULL_IMAGE:figures/full_fig_p006_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: Evolution of the solar wind plasma distribution in the [PITH_FULL_IMAGE:figures/full_fig_p007_5.png] view at source ↗

discussion (0)

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Reference graph

Works this paper leans on

65 extracted references · 15 canonical work pages

  1. [1]

    , keywords =

    Solar Wind Turbulence and the Role of Ion Instabilities. , keywords =. doi:10.1007/s11214-013-0004-8 , archivePrefix =. 1306.5336 , primaryClass =

    Pith/arXiv arXiv

  2. [2]

    Measuring the Coronal Plasma and Magnetic Field, Plasma Waves and Turbulence, and Radio Signatures of Solar Transients

    The FIELDS Instrument Suite for Solar Probe Plus. Measuring the Coronal Plasma and Magnetic Field, Plasma Waves and Turbulence, and Radio Signatures of Solar Transients. , keywords =. doi:10.1007/s11214-016-0244-5 , adsurl =

    doi:10.1007/s11214-016-0244-5

  3. [3]

    , keywords =

    Enhanced Energy Transfer Rate in Solar Wind Turbulence Observed near the Sun from Parker Solar Probe. , keywords =. doi:10.3847/1538-4365/ab5dae , archivePrefix =. 1912.02959 , primaryClass =

    Pith/arXiv arXiv 1912

  4. [4]

    , keywords =

    Extended Cyclotron Resonant Heating of the Turbulent Solar Wind. , keywords =. doi:10.3847/2041-8213/ad6b2e , archivePrefix =. 2406.10446 , primaryClass =

    Pith/arXiv arXiv 2041

  5. [5]

    Proceedings of the Royal Society of London Series A , year = 1956, month = jul, volume =

    The Boltzmann Equation and the One-Fluid Hydromagnetic Equations in the Absence of Particle Collisions. Proceedings of the Royal Society of London Series A , year = 1956, month = jul, volume =. doi:10.1098/rspa.1956.0116 , adsurl =

    arXiv 1956

  6. [6]

    Physics of Plasmas , keywords =

    Closure of fluid equations in collisionless magnetoplasmas. Physics of Plasmas , keywords =. doi:10.1063/1.2138568 , adsurl =

    doi:10.1063/1.2138568

  7. [7]

    , keywords =

    Variable Cascade Dynamics and Intermittency in the Solar Wind at 1 AU. , keywords =. doi:10.1088/0004-637X/786/1/52 , adsurl =

    work page doi:10.1088/0004-637x/786/1/52

  8. [8]

    arXiv e-prints , keywords =

    The Effect of Expansion and Instabilities in the Thermodynamic Regulation of the Young Solar Wind Plasma. arXiv e-prints , keywords =. doi:10.48550/arXiv.2603.25443 , archivePrefix =. 2603.25443 , primaryClass =

    work page doi:10.48550/arxiv.2603.25443

  9. [9]

    , keywords =

    Statistical Analysis of the Radial Evolution of the Solar Winds between 0.1 and 1 au and Their Semiempirical Isopoly Fluid Modeling. , keywords =. doi:10.3847/1538-4357/ac9b14 , archivePrefix =. 2207.03898 , primaryClass =

    Pith/arXiv arXiv

  10. [10]

    , keywords =

    Radial Evolution of Solar Wind Turbulence during Earth and Ulysses Alignment of 2007 August. , keywords =. doi:10.1088/0004-637X/717/1/474 , adsurl =

    work page doi:10.1088/0004-637x/717/1/474 2007

  11. [11]

    , keywords =

    On the slow solar wind with high Alfv \'e nicity: from composition and microphysics to spectral properties. , keywords =. doi:10.1093/mnras/sty3329 , archivePrefix =. 1812.01899 , primaryClass =

    Pith/arXiv arXiv

  12. [12]

    Journal of Geophysical Research (Space Physics) , keywords =

    On Alfv \'e nic Slow Wind: A Journey From the Earth Back to the Sun. Journal of Geophysical Research (Space Physics) , keywords =. doi:10.1029/2020JA028996 , adsurl =

    work page doi:10.1029/2020ja028996

  13. [13]

    Pressure anisotropy and small spatial scales induced by velocity shear. Phys. Rev. E , keywords =. doi:10.1103/PhysRevE.93.053203 , url =

    work page doi:10.1103/physreve.93.053203

  14. [14]

    , keywords =

    Solar wind electrons. , keywords =. doi:10.1029/JA080i031p04181 , adsurl =

    doi:10.1029/ja080i031p04181

  15. [15]

    , keywords =

    The Solar Probe Plus Mission: Humanity's First Visit to Our Star. , keywords =. doi:10.1007/s11214-015-0211-6 , adsurl =

    doi:10.1007/s11214-015-0211-6

  16. [16]

    Theory of Space Plasma Microinstabilities

  17. [17]

    , keywords =

    Nonlinear wave evolution in the expanding solar wind. , keywords =. doi:10.1103/PhysRevLett.70.2190 , adsurl =

    doi:10.1103/physrevlett.70.2190

  18. [18]

    , keywords =

    Inhomogeneous kinetic effects related to intermittent magnetic discontinuities. , keywords =. doi:10.1103/PhysRevE.86.066405 , adsurl =

    work page doi:10.1103/physreve.86.066405

  19. [19]

    Journal of Geophysical Research (Space Physics) , keywords =

    Dependence of the Interplanetary Magnetic Field on Heliocentric Distance at 0.3-1.7 AU: A Six-Spacecraft Study. Journal of Geophysical Research (Space Physics) , keywords =. doi:10.1029/2019JA027139 , adsurl =

    doi:10.1029/2019ja027139

  20. [20]

    , keywords =

    Solar wind proton temperature anisotropy: Linear theory and WIND/SWE observations. , keywords =. doi:10.1029/2006GL025925 , adsurl =

    doi:10.1029/2006gl025925

  21. [21]

    Journal of Geophysical Research (Space Physics) , keywords =

    Oblique proton fire hose instability in the expanding solar wind: Hybrid simulations. Journal of Geophysical Research (Space Physics) , keywords =. doi:10.1029/2008JA013416 , adsurl =

    doi:10.1029/2008ja013416

  22. [22]

    , keywords =

    Plasma Turbulence and Kinetic Instabilities at Ion Scales in the Expanding Solar Wind. , keywords =. doi:10.1088/2041-8205/811/2/L32 , archivePrefix =. 1508.03159 , primaryClass =

    Pith/arXiv arXiv 2041

  23. [23]

    , keywords =

    Turbulence versus Fire-hose Instabilities: 3D Hybrid Expanding Box Simulations. , keywords =. doi:10.3847/1538-4357/ab3e01 , archivePrefix =. 1908.07760 , primaryClass =

    Pith/arXiv arXiv 1908

  24. [24]

    Hellinger and V

    P. Hellinger and V. Montagud-Camps and L. Franci and L. Matteini and E. Papini and A. Verdini and S. Landi. Ion-scale transition of plasma turbulence: Pressure-strain effect. doi:10.3847/1538-4357/ac5fad

    doi:10.3847/1538-4357/ac5fad

  25. [25]

    , keywords =

    The Solar Orbiter magnetometer. , keywords =. doi:10.1051/0004-6361/201937257 , adsurl =

    doi:10.1051/0004-6361/201937257

  26. [26]

    , keywords =

    The Temperature Anisotropy and Helium Abundance Features of Alfv \'e nic Slow Solar Wind Observed by Parker Solar Probe, Helios, and Wind Missions. , keywords =. doi:10.3847/2041-8213/ade0ac , archivePrefix =. 2005.12372 , primaryClass =

    Pith/arXiv arXiv 2041

  27. [27]

    , keywords =

    On the Parallel and Oblique Firehose Instability in Fluid Models. , keywords =. doi:10.3847/1538-4357/aa64e3 , archivePrefix =. 1703.06221 , primaryClass =

    Pith/arXiv arXiv

  28. [28]

    An introductory guide to fluid models with anisotropic temperatures. Part 1. CGL description and collisionless fluid hierarchy. Journal of Plasma Physics , keywords =. doi:10.1017/S0022377819000801 , archivePrefix =. 1901.09354 , primaryClass =

    Pith/arXiv arXiv 1901

  29. [29]

    , keywords =

    Probing the Evolution of Solar Wind Temperature Anisotropies in the Inner Heliosphere. , keywords =. doi:10.3847/2041-8213/ae2792 , adsurl =

    work page doi:10.3847/2041-8213/ae2792 2041

  30. [30]

    , keywords =

    Solar Wind Electrons Alphas and Protons (SWEAP) Investigation: Design of the Solar Wind and Coronal Plasma Instrument Suite for Solar Probe Plus. , keywords =. doi:10.1007/s11214-015-0206-3 , adsurl =

    doi:10.1007/s11214-015-0206-3

  31. [31]

    , keywords =

    Ion-scale Turbulence and Energy Cascade Rate in the Solar Corona and Inner Heliosphere. , keywords =. doi:10.3847/2041-8213/ae09b0 , archivePrefix =. 2509.17861 , primaryClass =

    arXiv 2041

  32. [32]

    , keywords =

    The Solar Probe ANalyzer-Ions on the Parker Solar Probe. , keywords =. doi:10.3847/1538-4357/ac93f5 , adsurl =

    doi:10.3847/1538-4357/ac93f5

  33. [33]

    , keywords =

    Anticorrelation between the Bulk Speed and the Electron Temperature in the Pristine Solar Wind: First Results from the Parker Solar Probe and Comparison with Helios. , keywords =. doi:10.3847/1538-4365/ab61fc , adsurl =

    doi:10.3847/1538-4365/ab61fc

  34. [34]

    Sheffield Space Plasma Meeting: Multipoint Measurements versus Theory , year = 2001, editor =

    Intermittency in the Solar Wind Turbulence and the Haar Wavelet Transform. Sheffield Space Plasma Meeting: Multipoint Measurements versus Theory , year = 2001, editor =

    2001

  35. [35]

    , keywords =

    Solar wind protons: Three-dimensional velocity distributions and derived plasma parameters measured between 0.3 and 1 AU. , keywords =. doi:10.1029/JA087iA01p00052 , adsurl =

    doi:10.1029/ja087ia01p00052

  36. [36]

    , keywords =

    Solar wind helium ions: obsevations of the Helios solar probes between 0.3 and 1 AU. , keywords =. doi:10.1029/JA087iA01p00035 , adsurl =

    doi:10.1029/ja087ia01p00035

  37. [37]

    , keywords =

    On the equaton of state of solar wind ions derived from Helios measurements. , keywords =. doi:10.1029/JA088iA04p02982 , adsurl =

    work page doi:10.1029/ja088ia04p02982

  38. [38]

    , keywords =

    Helios: Evolution of Distribution Functions 0.3-1 AU. , keywords =. doi:10.1007/s11214-010-9734-z , adsurl =

    doi:10.1007/s11214-010-9734-z

  39. [39]

    Journal of Geophysical Research (Space Physics) , keywords =

    Parallel proton fire hose instability in the expanding solar wind: Hybrid simulations. Journal of Geophysical Research (Space Physics) , keywords =. doi:10.1029/2006JA011667 , adsurl =

    doi:10.1029/2006ja011667

  40. [40]

    , keywords =

    Evolution of the solar wind proton temperature anisotropy from 0.3 to 2.5 AU. , keywords =. doi:10.1029/2007GL030920 , adsurl =

    doi:10.1029/2007gl030920

  41. [41]

    , keywords =

    Ion Kinetics in the Solar Wind: Coupling Global Expansion to Local Microphysics. , keywords =. doi:10.1007/s11214-011-9774-z , adsurl =

    work page doi:10.1007/s11214-011-9774-z

  42. [42]

    , keywords =

    The Turbulent Cascade at 1 AU: Energy Transfer and the Third-Order Scaling for MHD. , keywords =. doi:10.1086/529575 , adsurl =

    work page doi:10.1086/529575

  43. [43]

    , keywords =

    Scaling laws for the energy transfer in space plasma turbulence. , keywords =. doi:10.1016/j.physrep.2022.12.001 , adsurl =

    doi:10.1016/j.physrep.2022.12.001 2022

  44. [44]

    Journal of Geophysical Research (Space Physics) , keywords =

    Signatures of kinetic instabilities in the solar wind. Journal of Geophysical Research (Space Physics) , keywords =. doi:10.1002/jgra.50320 , adsurl =

    work page doi:10.1002/jgra.50320

  45. [45]

    Journal of Geophysical Research (Space Physics) , keywords =

    Quasi-thermal noise spectroscopy: The art and the practice. Journal of Geophysical Research (Space Physics) , keywords =. doi:10.1002/2017JA024449 , adsurl =

    work page doi:10.1002/2017ja024449

  46. [46]

    , keywords =

    First In Situ Measurements of Electron Density and Temperature from Quasi-thermal Noise Spectroscopy with Parker Solar Probe/FIELDS. , keywords =. doi:10.3847/1538-4365/ab5a84 , archivePrefix =. 1912.02518 , primaryClass =

    Pith/arXiv arXiv 1912

  47. [47]

    , keywords =

    Direct observation of solar wind proton heating from in situ plasma measurements. , keywords =. doi:10.1051/0004-6361/202346202 , adsurl =

    work page doi:10.1051/0004-6361/202346202

  48. [48]

    , keywords =

    The Solar Orbiter Solar Wind Analyser (SWA) suite. , keywords =. doi:10.1051/0004-6361/201937259 , adsurl =

    doi:10.1051/0004-6361/201937259

  49. [49]

    2026 , month =

    Payne, Dominic and Akhavan-Tafti, Mojtaba and Velli, Marco and Zank, Gary and Rivera, Yeimy , title =. 2026 , month =. doi:10.3847/2041-8213/ae7bef , url =

    work page doi:10.3847/2041-8213/ae7bef 2026

  50. [50]

    , keywords =

    Radial evolution of the solar wind in pure high-speed streams: HELIOS revised observations. , keywords =. doi:10.1093/mnras/sty3348 , archivePrefix =. 1810.04014 , primaryClass =

    Pith/arXiv arXiv

  51. [51]

    , keywords =

    Dissipation measures in weakly collisional plasmas. , keywords =. doi:10.1093/mnras/stab1516 , archivePrefix =. 2101.00722 , primaryClass =

    Pith/arXiv arXiv

  52. [52]

    , keywords =

    The radial evolution of a single solar wind plasma parcel. , keywords =. doi:10.1029/JA088iA12p09919 , adsurl =

    doi:10.1029/ja088ia12p09919

  53. [53]

    Large-Scale Phenomena

    Physics of the Inner Heliosphere I. Large-Scale Phenomena. doi:10.1007/978-3-642-75361-9 , adsurl =

    doi:10.1007/978-3-642-75361-9

  54. [54]

    , keywords =

    A New Inner Heliosphere Proton Parameter Dataset from the Helios Mission. , keywords =. doi:10.1007/s11207-018-1377-3 , archivePrefix =. 1807.04376 , primaryClass =

    Pith/arXiv arXiv

  55. [55]

    Journal of Geophysical Research (Space Physics) , keywords =

    ``Illuminating'' electron diffusion regions of collisionless magnetic reconnection using electron agyrotropy. Journal of Geophysical Research (Space Physics) , keywords =. doi:10.1029/2008JA013035 , adsurl =

    doi:10.1029/2008ja013035

  56. [56]

    Journal of Plasma Physics , year = 2015, month = jan, volume =

    A kinetic model of plasma turbulence. Journal of Plasma Physics , year = 2015, month = jan, volume =. doi:10.1017/S0022377814000841 , adsurl =

    doi:10.1017/s0022377814000841 2015

  57. [57]

    , keywords =

    Quiescent Solar Wind Regions in the Near-Sun Environment: Properties and Radial Evolution. , keywords =. doi:10.3847/1538-4357/ad7b13 , archivePrefix =. 2406.00174 , primaryClass =

    Pith/arXiv arXiv

  58. [58]

    Journal of Geophysical Research (Space Physics) , keywords =

    Electron temperature anisotropy constraints in the solar wind. Journal of Geophysical Research (Space Physics) , keywords =. doi:10.1029/2007JA012733 , adsurl =

    doi:10.1029/2007ja012733

  59. [59]

    Journal of Geophysical Research (Space Physics) , keywords =

    Radial evolution of nonthermal electron populations in the low-latitude solar wind: Helios, Cluster, and Ulysses Observations. Journal of Geophysical Research (Space Physics) , keywords =. doi:10.1029/2008JA013883 , adsurl =

    doi:10.1029/2008ja013883

  60. [60]

    , keywords =

    Quantifying gyrotropy in magnetic reconnection. , keywords =. doi:10.1002/2015GL066980 , archivePrefix =. 1509.00787 , primaryClass =

    Pith/arXiv arXiv

  61. [61]

    Journal of Geophysical Research (Space Physics) , keywords =

    Evaluation of the turbulent energy cascade rates from the upper inertial range in the solar wind at 1 AU. Journal of Geophysical Research (Space Physics) , keywords =. doi:10.1029/2007JA012305 , adsurl =

    work page doi:10.1029/2007ja012305

  62. [62]

    Frontiers in Astronomy and Space Sciences , keywords =

    Electron-Driven Instabilities in the Solar Wind. Frontiers in Astronomy and Space Sciences , keywords =. doi:10.3389/fspas.2022.951628 , archivePrefix =. 2206.10403 , primaryClass =

    arXiv 2022

  63. [63]

    Yang and W

    Y. Yang and W. H. Matthaeus and T. N. Parashar and C. C. Haggerty and V. Roytershteyn and W. Daughton and M. Wan and Y. Shi and S. Chen. Energy transfer, pressure tensor, and heating of kinetic plasma. Physics of Plasmas , year = 2017, volume = 24, eid =

    2017

  64. [64]

    , keywords =

    Solar Wind Heating near the Sun: A Radial Evolution Approach. , keywords =. doi:10.3847/1538-4357/ae4582 , archivePrefix =. 2602.10275 , primaryClass =

    arXiv

  65. [65]

    Geophysical Research Letters , keywords =

    On the Evaluation of Solar Wind's Heating Rates. Geophysical Research Letters , keywords =. doi:10.1029/2022GL101548 , archivePrefix =. 2211.09650 , primaryClass =

    Pith/arXiv arXiv