Articles de revues : « Inner-Heliosphere »

1

Hewish, A. « Physics of the inner Heliosphere ». Journal of Atmospheric and Terrestrial Physics 54, n^o 7-8 (juillet 1992) : 1085. http://dx.doi.org/10.1016/0021-9169(92)90076-w.

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Luhmann, Janet G. « The Inner Heliosphere at Fifty ». Eos, Transactions American Geophysical Union 94, n^o 38 (17 septembre 2013) : 329–30. http://dx.doi.org/10.1002/2013eo380001.

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Vogt, A., B. Heber, A. Kopp, M. S. Potgieter et R. D. Strauss. « Jovian electrons in the inner heliosphere ». Astronomy & ; Astrophysics 613 (mai 2018) : A28. http://dx.doi.org/10.1051/0004-6361/201731736.

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Context. Since the Pioneer 10 flyby of Jupiter it has become well known that electrons of Jovian origin dominate the lower MeV range of charged energetic particles in the inner heliosphere. Aims. Because the Jovian source can be treated as point-like in numerical models, many attempts to investigate charged particle transport in the inner heliosphere have utilized Jovian electrons as test particles. The reliability of the derived parameters for convective and diffusive transport processes are therefore highly dependent on an accurate estimation of the Jovian source spectrum. In this study we aim to provide such an estimation. Methods. In this study we have proposed a new electron source spectrum, specified at the boundary of the Jovian magnetosphere, fitted to flyby measurements by Pioneer 10 and Ulysses, with a spectral shape also in agreement with measurements at Earth’s orbit by Ulysses, Voyager 1, ISEE and SOHO. Results. The proposed spectrum is consistent with all previous theoretical suggestions, but deviates considerably in the lower MeV range which was inaccessible to those studies.

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Kallenrode, May Britt. « Particle propagation in the inner heliosphere ». Journal of Geophysical Research : Space Physics 98, A11 (1 novembre 1993) : 19037–47. http://dx.doi.org/10.1029/93ja02079.

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Nkosi, G. S., M. S. Potgieter et S. E. S. Ferreira. « Electron anisotropies in the inner heliosphere ». Planetary and Space Science 56, n^o 3-4 (mars 2008) : 501–9. http://dx.doi.org/10.1016/j.pss.2007.10.003.

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Tenerani, Anna, Nikos Sioulas, Lorenzo Matteini, Olga Panasenco, Chen Shi et Marco Velli. « Evolution of Switchbacks in the Inner Heliosphere ». Astrophysical Journal Letters 919, n^o 2 (1 octobre 2021) : L31. http://dx.doi.org/10.3847/2041-8213/ac2606.

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Tenerani, Anna, Nikos Sioulas, Lorenzo Matteini, Olga Panasenco, Chen Shi et Marco Velli. « Evolution of Switchbacks in the Inner Heliosphere ». Astrophysical Journal Letters 919, n^o 2 (1 octobre 2021) : L31. http://dx.doi.org/10.3847/2041-8213/ac2606.

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Stansby, D., et T. S. Horbury. « Number density structures in the inner heliosphere ». Astronomy & ; Astrophysics 613 (mai 2018) : A62. http://dx.doi.org/10.1051/0004-6361/201732567.

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Aims. The origins and generation mechanisms of the slow solar wind are still unclear. Part of the slow solar wind is populated by number density structures, discrete patches of increased number density that are frozen in to and move with the bulk solar wind. In this paper we aimed to provide the first in-situ statistical study of number density structures in the inner heliosphere. Methods. We reprocessed in-situ ion distribution functions measured by Helios in the inner heliosphere to provide a new reliable set of proton plasma moments for the entire mission. From this new data set we looked for number density structures measured within 0.5 AU of the Sun and studied their properties. Results. We identified 140 discrete areas of enhanced number density. The structures occurred exclusively in the slow solar wind and spanned a wide range of length scales from 50 Mm to 2000 Mm, which includes smaller scales than have been previously observed. They were also consistently denser and hotter that the surrounding plasma, but had lower magnetic field strengths, and therefore remained in pressure balance. Conclusions. Our observations show that these structures are present in the slow solar wind at a wide range of scales, some of which are too small to be detected by remote sensing instruments. These structures are rare, accounting for only 1% of the slow solar wind measured by Helios, and are not a significant contribution to the mass flux of the solar wind.

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Chashei, I. V. « Turbulence dissipation scale in the inner heliosphere ». Advances in Space Research 20, n^o 12 (janvier 1997) : 2299–302. http://dx.doi.org/10.1016/s0273-1177(97)00903-4.

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Davila, Joseph M. « Observing the inner heliosphere from new perspectives ». Advances in Space Research 21, n^o 1-2 (janvier 1998) : 319–23. http://dx.doi.org/10.1016/s0273-1177(97)00988-5.

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Clem, John, Paul Evenson et Bernd Heber. « Cosmic electron gradients in the inner heliosphere ». Geophysical Research Letters 29, n^o 23 (décembre 2002) : 11–1. http://dx.doi.org/10.1029/2002gl015532.

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McKibben, R. B. « Cosmic-ray diffusion in the inner heliosphere ». Advances in Space Research 35, n^o 4 (janvier 2005) : 518–31. http://dx.doi.org/10.1016/j.asr.2005.01.022.

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Bisoi, Susanta Kumar, et P. Janardhan. « Interplanetary scintillation signatures in the inner heliosphere of the deepest solar minimum in the past 100 years ». Proceedings of the International Astronomical Union 8, S294 (août 2012) : 83–84. http://dx.doi.org/10.1017/s1743921313002299.

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AbstractWe have used interplanetary scintillation (IPS) observations at 327 MHz spanning years 1983-2009 to study microturbulence levels in the inner heliosphere. We find that the microturbulence levels show a steady and significant drop in the entire inner heliosphere starting from around 1995. The fact that the solar polar fields have also shown a similar declining trend provides a consistent result showing the buildup to the solar minimum between the solar cycles 23 and 24, the deepest in the past 100 years, actually began more than a decade earlier.

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Livadiotis. « Connection of Turbulence with Polytropic Index in the Solar Wind Proton Plasma ». Entropy 21, n^o 11 (25 octobre 2019) : 1041. http://dx.doi.org/10.3390/e21111041.

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This paper improves our understanding of the interplay of the proton plasma turbulent heating sources of the expanding solar wind in the heliosphere. Evidence is shown of the connections between the polytropic index, the rate of the heat absorbed by the solar wind, and the rate of change of the turbulent energy, which heats the solar wind in the inner and outer heliosphere. In particular, we: (i) show the theoretical connection of the rate of a heat source, such as the turbulent energy, with the polytropic index and the thermodynamic process; (ii) calculate the effect of the pick-up protons in the total proton temperature and the relationship connecting the rate of heating with the polytropic index; (iii) derive the radial profiles of the solar wind heating in the outer and inner heliosphere; and (iv) use the radial profile of the turbulent energy in the solar wind proton plasma in the heliosphere, in order to show its connection with the radial profiles of the polytropic index and the heating of the solar wind.

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Pomoell, Jens, et S. Poedts. « EUHFORIA : European heliospheric forecasting information asset ». Journal of Space Weather and Space Climate 8 (2018) : A35. http://dx.doi.org/10.1051/swsc/2018020.

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The implementation and first results of the new space weather forecasting-targeted inner heliosphere model “European heliospheric forecasting information asset” (EUHFORIA) are presented. EUHFORIA consists of two major components: a coronal model and a heliosphere model including coronal mass ejections. The coronal model provides data-driven solar wind plasma parameters at 0.1 AU by constructing a magnetic field model of the coronal large-scale magnetic field and employing empirical relations to determine the plasma state such as the solar wind speed and mass density. These are then used as boundary conditions to drive a three-dimensional time-dependent magnetohydrodynamics model of the inner heliosphere up to 2 AU. CMEs are injected into the ambient solar wind modeled using the cone model, with their parameters obtained from fits to imaging observations. In addition to detailing the modeling methodology, an initial validation run is presented. The results feature a highly dynamic heliosphere that the model is able to capture in good agreement with in situ observations. Finally, future horizons for the model are outlined.

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Krainev, Mikhail, Mikhail Kalinin, Galina Bazilevskaya, Albina Svirzhevskaya, Nikolay Svirzhevsky, Xi Luo, O. P. M. Aslam, F. Shen, M. D. Ngobeni et M. S. Potgieter. « Manifestation of solar wind corotating interaction regions in GCR intensity variations ». Solnechno-Zemnaya Fizika 9, n^o 1 (28 mars 2023) : 10–21. http://dx.doi.org/10.12737/szf-91202302.

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The regions of interaction between solar wind streams of different speed, known as corotating interaction regions, form an almost constantly existing structure of the inner heliosphere. Using observational data on the main characteristics of the heliosphere, important for GCR modulation, and the results of 3D MHD modeling of corotating interaction regions, and Monte Carlo simulation of recurrent GCR variations, we analyze the importance of the corotating interaction regions for longitude-averaged characteristics of the heliosphere and GCR propagation, and possible ways for simulating long-term GCR intensity variations with respect to the corotating interaction regions.

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Krainev, Mikhail, Mikhail Kalinin, Galina Bazilevskaya, Albina Svirzhevskaya, Nikolay Svirzhevsky, Xi Luo, O. P. M. Aslam, F. Shen, M. D. Ngobeni et M. S. Potgieter. « Manifestation of solar wind corotating interaction regions in GCR intensity variations ». Solar-Terrestrial Physics 9, n^o 1 (28 mars 2023) : 9–20. http://dx.doi.org/10.12737/stp-91202302.

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The regions of interaction between solar wind streams of different speed, known as corotating interaction regions, form an almost constantly existing structure of the inner heliosphere. Using observational data on the main characteristics of the heliosphere, important for GCR modulation, and the results of 3D MHD modeling of corotating interaction regions, and Monte Carlo simulation of recurrent GCR variations, we analyze the importance of the corotating interaction regions for longitude-averaged characteristics of the heliosphere and GCR propagation, and possible ways for simulating long-term GCR intensity variations with respect to the corotating interaction regions.

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Bowen, Trevor A., Alfred Mallet, Jia Huang, Kristopher G. Klein, David M. Malaspina, Michael Stevens, Stuart D. Bale et al. « Ion-scale Electromagnetic Waves in the Inner Heliosphere ». Astrophysical Journal Supplement Series 246, n^o 2 (6 février 2020) : 66. http://dx.doi.org/10.3847/1538-4365/ab6c65.

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Adhikari, L., G. P. Zank, L. L. Zhao et D. Telloni. « MHD Turbulent Power Anisotropy in the Inner Heliosphere ». Astrophysical Journal 933, n^o 1 (1 juillet 2022) : 56. http://dx.doi.org/10.3847/1538-4357/ac70cb.

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Abstract We study anisotropic magnetohydrodynamic (MHD) turbulence in the slow solar wind measured by Parker Solar Probe (PSP) and Solar Orbiter (SolO) during its first orbit from the perspective of variance anisotropy and correlation anisotropy. We use the Belcher & Davis approach (M1) and a new method (M2) that decomposes a fluctuating vector into parallel and perpendicular fluctuating vectors. M1 and M2 calculate the transverse and parallel turbulence components relative to the mean magnetic field direction. The parallel turbulence component is regarded as compressible turbulence, and the transverse turbulence component as incompressible turbulence, which can be either Alfvénic or 2D. The transverse turbulence energy is calculated from M1 and M2, and the transverse correlation length from M2. We obtain the 2D and slab turbulence energy and the corresponding correlation lengths from those transverse turbulence components that satisfy an angle between the mean solar wind flow speed and mean magnetic field θ UB of either (i) 65° < θ UB < 115° or (ii) 0° < θ UB < 25° (155° < θ UB < 180°), respectively. We find that the 2D turbulence component is not typically observed by PSP near perihelion, but the 2D component dominates turbulence in the inner heliosphere. We compare the detailed theoretical results of a nearly incompressible MHD turbulence transport model with the observed results of PSP and SolO measurements, finding good agreement between them.

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Ramanjooloo, Y. « How comets reveal structure of the inner heliosphere ». Astronomy & ; Geophysics 55, n^o 1 (24 janvier 2014) : 1.32–1.35. http://dx.doi.org/10.1093/astrogeo/atu038.

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Li, Gang. « Particle acceleration and transport in the inner heliosphere ». Science China Earth Sciences 60, n^o 8 (19 juillet 2017) : 1440–65. http://dx.doi.org/10.1007/s11430-017-9083-y.

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Lange, D., et H. Fichtner. « Are there Kronian electrons in the inner heliosphere ? » Astronomy & ; Astrophysics 482, n^o 3 (4 mars 2008) : 973–79. http://dx.doi.org/10.1051/0004-6361:20079069.

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Merkin, V. G., J. G. Lyon, D. Lario, C. N. Arge et C. J. Henney. « Time‐dependent magnetohydrodynamic simulations of the inner heliosphere ». Journal of Geophysical Research : Space Physics 121, n^o 4 (avril 2016) : 2866–90. http://dx.doi.org/10.1002/2015ja022200.

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Sioulas, Nikos, Zesen Huang, Chen Shi, Marco Velli, Anna Tenerani, Trevor A. Bowen, Stuart D. Bale et al. « Magnetic Field Spectral Evolution in the Inner Heliosphere ». Astrophysical Journal Letters 943, n^o 1 (1 janvier 2023) : L8. http://dx.doi.org/10.3847/2041-8213/acaeff.

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Abstract Parker Solar Probe and Solar Orbiter data are used to investigate the radial evolution of magnetic turbulence between 0.06 ≲ R ≲ 1 au. The spectrum is studied as a function of scale, normalized to the ion inertial scale d i . In the vicinity of the Sun, the inertial range is limited to a narrow range of scales and exhibits a power-law exponent of, α B = −3/2, independent of plasma parameters. The inertial range grows with distance, progressively extending to larger spatial scales, while steepening toward a α B = −5/3 scaling. It is observed that spectra for intervals with large magnetic energy excesses and low Alfvénic content steepen significantly with distance, in contrast to highly Alfvénic intervals that retain their near-Sun scaling. The occurrence of steeper spectra in slower wind streams may be attributed to the observed positive correlation between solar wind speed and Alfvénicity.

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He, Jiansen, Ying Wang, Xingyu Zhu, Die Duan, Daniel Verscharen et Guoqing Zhao. « Growth of Outward Propagating Fast-magnetosonic/Whistler Waves in the Inner Heliosphere Observed by Parker Solar Probe ». Astrophysical Journal 933, n^o 2 (1 juillet 2022) : 220. http://dx.doi.org/10.3847/1538-4357/ac6c8e.

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Abstract The solar wind in the inner heliosphere has been observed by Parker Solar Probe (PSP) to exhibit abundant wave activities. The cyclotron wave modes responding to ions or electrons are among the most crucial wave components. However, their origin and evolution in the inner heliosphere close to the Sun remains a mystery. Specifically, it remains unknown whether it is an emitted signal from the solar atmosphere or an eigenmode growing locally in the heliosphere due to plasma instability. To address and resolve this controversy, we must investigate the key quantity of the energy change rate of the wave mode. We develop a new technique to measure the energy change rate of plasma waves, and apply this technique to the wave electromagnetic fields measured by PSP. We provide the wave Poynting flux in the solar wind frame, identify the wave nature to be the outward propagating fast-magnetosonic/whistler wave mode instead of the sunward propagating waves. We provide the first evidence for growth of the fast-magnetosonic/whistler wave mode in the inner heliosphere based on the derived spectra of the real and imaginary parts of the wave frequencies. The energy change rate rises and stays at a positive level in the same wavenumber range as the bumps of the electromagnetic field power spectral densities, clearly manifesting that the observed fast-magnetosonic/whistler waves are locally growing to a large amplitude.

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Lugaz, Noé, Charles J. Farrugia et Nada Al-Haddad. « Complex Evolution of Coronal Mass Ejections in the Inner Heliosphere as Revealed by Numerical Simulations and STEREO Observations : A Review ». Proceedings of the International Astronomical Union 8, S300 (juin 2013) : 255–64. http://dx.doi.org/10.1017/s174392131301106x.

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AbstractThe transit of coronal mass ejections (CMEs) from the Sun to 1 AU lasts on average one to five days. As they propagate, CMEs interact with the solar wind and preceding eruptions, which modify their properties. In the past ten years, the evolution of CMEs in the inner heliosphere has been investigated with the help of numerical simulations, through the analysis of remote-sensing heliospheric observations, especially with the SECCHI suite onboard STEREO, and through the analysis of multi-spacecraft in situ measurements. Most studies have focused on understanding the characteristics of the magnetic flux rope thought to form the core of the CME. Here, we first review recent work related to CME propagation in the heliosphere, which point towards the need to develop more complex models to analyze CME observations. In the second part of this article, we review some recent studies of CME-CME interaction, which also illustrate the complexity of phenomena occurring in the inner heliosphere.

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Riley, Pete, Jon A. Linker et Zoran Mikic. « Global MHD Modeling of the Solar Corona and Inner Heliosphere for the Whole Heliosphere Interval ». Proceedings of the International Astronomical Union 5, H15 (novembre 2009) : 491–93. http://dx.doi.org/10.1017/s1743921310010367.

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AbstractWith the goal of understanding the three-dimensional structure of the solar corona and inner heliosphere during the “Whole Heliosphere Interval” (WHI), we have developed a global MHD solution for Carrington rotation (CR) 2068. Our model, which includes energy transport processes, such as coronal heating, conduction of heat parallel to the magnetic field, radiative losses, and the effects of Alfvén waves, is capable of producing significantly better estimates of the plasma temperature and density in the corona than have been possible in the past. With such a model, we can compute emission in extreme ultraviolet (EUV) and X-ray wavelengths, as well as scattering in polarized white light. Additionally, from our heliospheric solutions, we can deduce magnetic field and plasma parameters along specific spacecraft trajectories. We have made detailed comparisons of both remote solar and in situ observations with the model results, allowing us to: (1) Connect these disparate sets of observations; (2) Infer the global structure of the inner heliosphere; and (3) Provide support for (or against) assumptions in the MHD model, such as the empirically-based coronal heating profiles.

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Vogt, A., N. E. Engelbrecht, R. D. Strauss, B. Heber, A. Kopp et K. Herbst. « The residence-time of Jovian electrons in the inner heliosphere ». Astronomy & ; Astrophysics 642 (octobre 2020) : A170. http://dx.doi.org/10.1051/0004-6361/201936897.

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Context. Jovian electrons serve an important role in test-particle distribution in the inner heliosphere. They have been used extensively in the past to study the (diffusive) transport of cosmic rays in the inner heliosphere. With new limits on the Jovian source function, that is, the particle intensity just outside the Jovian magnetosphere, and a new set of in-situ observations at 1 AU for cases of both good and poor magnetic connection between the source and observer, we revisit some of these earlier simulations. Aims. We aim to find the optimal numerical set-up that can be used to simulate the propagation of 6 MeV Jovian electrons in the inner heliosphere. Using such a setup, we further aim to study the residence (propagation) times of these particles for different levels of magnetic connection between Jupiter and an observer at Earth (1 AU). Methods. Using an advanced Jovian electron propagation model based on the stochastic differential equation approach, we calculated the Jovian electron intensity for different model parameters. A comparison with observations leads to an optimal numerical setup, which was then used to calculate the so-called residence (propagation) times of these particles. Results. Through a comparison with in-situ observations, we were able to derive transport parameters that are appropriate for the study of the propagation of 6 MeV Jovian electrons in the inner heliosphere. Moreover, using these values, we show that the method of calculating the residence time applied in the existing literature is not suited to being interpreted as the propagation time of physical particles. This is due to an incorrect weighting of the probability distribution. We applied a new method, where the results from each pseudo-particle are weighted by its resulting phase-space density (i.e. the number of physical particles that it represents). We thereby obtained more reliable estimates for the propagation time.

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Strauss, R. D., J. P. van den Berg et J. S. Rankin. « Cosmic-Ray Transport near the Sun ». Astrophysical Journal 928, n^o 1 (1 mars 2022) : 22. http://dx.doi.org/10.3847/1538-4357/ac582a.

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Abstract The strongly diverging magnetic field lines in the very inner heliosphere, through the associated magnetic focusing/mirroring forces, can, potentially, lead to highly anisotropic galactic cosmic-ray distributions close to the Sun. Using a simplified analytical approach, validated by numerical simulations, we study the behavior of the galactic cosmic-ray distribution in this newly explored region of the heliosphere and find that significant anisotropies can be expected inside 0.2 au.

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Bisi, Mario M., B. V. Jackson, J. M. Clover, P. P. Hick, A. Buffington et M. Tokumaru. « A Summary of 3-D Reconstructions of the Whole Heliosphere Interval and Comparison with in-Ecliptic Solar Wind Measurements from STEREO, ACE, and Wind Instrumentation ». Proceedings of the International Astronomical Union 5, H15 (novembre 2009) : 480–83. http://dx.doi.org/10.1017/s1743921310010331.

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AbstractWe present a summary of results from simultaneous Solar-Terrestrial Environment Laboratory (STELab) Interplanetary Scintillation (IPS), STEREO, ACE, and Wind observations using three-dimensional reconstructions of the Whole Heliosphere Interval – Carrington rotation 2068. This is part of the world-wide IPS community's International Heliosphysical Year (IHY) collaboration. We show the global structure of the inner heliosphere and how our 3-D reconstructions compare with in-ecliptic spacecraft measurements.

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Mitchell, J. G., R. A. Leske, G. A. DE Nolfo, E. R. Christian, M. E. Wiedenbeck, D. J. McComas, C. M. S. Cohen et al. « First Measurements of Jovian Electrons by Parker Solar Probe/IS⊙IS within 0.5 au of the Sun ». Astrophysical Journal 933, n^o 2 (1 juillet 2022) : 171. http://dx.doi.org/10.3847/1538-4357/ac75ce.

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Abstract Energetic electrons of Jovian origin have been observed for decades throughout the heliosphere, as far as 11 au, and as close as 0.5 au, from the Sun. The treatment of Jupiter as a continuously emitting point source of energetic electrons has made Jovian electrons a valuable tool in the study of energetic electron transport within the heliosphere. We present observations of Jovian electrons measured by the EPI-Hi instrument in the Integrated Science Investigation of the Sun instrument suite on Parker Solar Probe at distances within 0.5 au of the Sun. These are the closest measurements of Jovian electrons to the Sun, providing a new opportunity to study the propagation and transport of energetic electrons to the inner heliosphere. We also find periods of nominal connection between the spacecraft and Jupiter in which expected Jovian electron enhancements are absent. Several explanations for these absent events are explored, including stream interaction regions between Jupiter and Parker Solar Probe and the spacecraft lying on the opposite side of the heliospheric current sheet from Jupiter, both of which could impede the flow of the electrons. These observations provide an opportunity to gain a greater insight into electron transport through a previously unexplored region of the inner heliosphere.

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Riley, P., R. Lionello, J. A. Linker, Z. Mikic, J. Luhmann et J. Wijaya. « Global MHD Modeling of the Solar Corona and Inner Heliosphere for the Whole Heliosphere Interval ». Solar Physics 274, n^o 1-2 (5 février 2011) : 361–77. http://dx.doi.org/10.1007/s11207-010-9698-x.

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Morales Olivares, O. G., et R. A. Caballero Lopez. « Radial intensity gradients of galactic cosmic rays in the heliosphere at solar maximum : 1D no-shock simulation ». Geofísica Internacional 48, n^o 2 (1 avril 2009) : 237–42. http://dx.doi.org/10.22201/igeof.00167169p.2009.48.2.2141.

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We study the spatial distribution of galactic cosmic rays in the heliosphere at solar maximum of cycles 21, 22 and 23, using a one-dimensional no-shock model of the cosmic ray transport equation. We investigate the radial intensity gradients from 1 AU to the distant heliosphere and interpret the data from IMP8, Voyagers 1 and 2, Pioneer 10 and balloon experiment BESS. We consider three physical processes that affect cosmic radiation: diffusion, convection and adiabatic energy loss. Our analysis indicates that adiabatic energy may play an impor- tant role in the radial distribution of galactic cosmic rays in the inner heliosphere. In the outer region diffusion and convection are the dominant processes.

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Ferreira, Stefan E. S. « Theory of cosmic ray modulation ». Proceedings of the International Astronomical Union 4, S257 (septembre 2008) : 429–38. http://dx.doi.org/10.1017/s1743921309029664.

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AbstractThis work aims to give a brief overview on the topic of cosmic ray modulation in the heliosphere. The heliosphere, heliospheric magnetic field, transport parameters and the transport equation together with modulation models, which solve this equation in various degree of complexity, are briefly discussed. Results from these models are then presented where first it is shown how cosmic rays are globally distributed in an asymmetrical heliosphere which results from the relative motion between the local interstellar medium and the Sun. Next the focus shifts to low-energy Jovian electrons. The intensities of these electrons, which originate from a point source in the inner heliosphere, exhibit a unique three-dimensional spiral structure where most of the particles are transported along the magnetic field lines. Time-dependent modulation is also discussed where it is shown how drift effects together with propagating diffusion barriers are responsible for modulation over a solar cycle.

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Baumann, Carsten, Margaretha Myrvang et Ingrid Mann. « Dust sputtering within the inner heliosphere : a modelling study ». Annales Geophysicae 38, n^o 4 (3 août 2020) : 919–30. http://dx.doi.org/10.5194/angeo-38-919-2020.

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Abstract. The aim of this study is to investigate through modelling how sputtering by impacting solar wind ions influences the lifetime of dust particles in the inner heliosphere near the Sun. We consider three typical dust materials, silicate, Fe0.4Mg0.6O, and carbon, and describe their sputtering yields based on atomic yields given by the Stopping and Range of Ions in Matter (SRIM) package. The influence of the solar wind is characterized by plasma density, solar wind speed, and solar wind composition, and we assume for these parameter values that are typical for fast solar wind, slow solar wind, and coronal mass ejection (CME) conditions to calculate the sputtering lifetimes of dust. To compare the sputtering lifetimes to typical sublimation lifetimes, we use temperature estimates based on Mie calculations and material vapour pressure derived with the MAGMA chemical equilibrium code. We also compare the sputtering lifetimes to the Poynting–Robertson lifetime and to the collision lifetime. We present a set of sputtering rates and lifetimes that can be used for estimating dust destruction in the fast and slow solar wind and during CME conditions. Our results can be applied to solid particles of a few nanometres and larger. The sputtering lifetimes increase linearly with the size of particles. We show that sputtering rates increase during CME conditions, primarily because of the high number densities of heavy ions in the CME plasma. The shortest sputtering lifetimes we find are for silicate, followed by Fe0.4Mg0.6O and carbon. In a comparison between sputtering and sublimation lifetimes we concentrate on the nanodust population. The comparison shows that sublimation is the faster destruction process within 0.1 AU for Fe0.4Mg0.6O, within 0.05 AU for carbon dust, and within 0.07 AU for silicate dust. The destruction by sputtering can play a role in the vicinity of the Sun. We discuss our findings in the context of recent F-corona intensity measurements onboard Parker Solar Probe.

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Klein, Kristopher G., Mihailo Martinović, David Stansby et Timothy S. Horbury. « Linear Stability in the Inner Heliosphere : Helios Re-evaluated ». Astrophysical Journal 887, n^o 2 (23 décembre 2019) : 234. http://dx.doi.org/10.3847/1538-4357/ab5802.

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Hajra, Rajkumar. « Variation of the Interplanetary Shocks in the Inner Heliosphere ». Astrophysical Journal 917, n^o 2 (1 août 2021) : 91. http://dx.doi.org/10.3847/1538-4357/ac0897.

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Comişel, H., U. Motschmann, J. Büchner, Y. Narita et Y. Nariyuki. « ION-SCALE TURBULENCE IN THE INNER HELIOSPHERE : RADIAL DEPENDENCE ». Astrophysical Journal 812, n^o 2 (21 octobre 2015) : 175. http://dx.doi.org/10.1088/0004-637x/812/2/175.

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Kallenrode, M. B., G. Wibberenz et S. Hucke. « Propagation conditions of relativistic electrons in the inner heliosphere ». Astrophysical Journal 394 (juillet 1992) : 351. http://dx.doi.org/10.1086/171587.

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Giacalone, J., J. R. Jokipii, R. B. Decker, S. M. Krimigis, M. Scholer et H. Kucharek. « Preacceleration of Anomalous Cosmic Rays in the Inner Heliosphere ». Astrophysical Journal 486, n^o 1 (septembre 1997) : 471–76. http://dx.doi.org/10.1086/304497.

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Hewish, A. « Imaging large scale plasma disturbances in the inner heliosphere ». Radiophysics and Quantum Electronics 37, n^o 5 (mai 1994) : 339–43. http://dx.doi.org/10.1007/bf01045684.

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Moser, M. R., E. O. Flückiger, J. M. Ryan, J. R. Macri et M. L. McConnell. « A fast neutron imaging telescope for inner heliosphere missions ». Advances in Space Research 36, n^o 8 (janvier 2005) : 1399–405. http://dx.doi.org/10.1016/j.asr.2005.03.037.

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Stumpo, Mirko, Virgilio Quattrociocchi, Simone Benella, Tommaso Alberti et Giuseppe Consolini. « Self-Organization through the Inner Heliosphere : Insights from Parker Solar Probe ». Atmosphere 12, n^o 3 (28 février 2021) : 321. http://dx.doi.org/10.3390/atmos12030321.

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The interplanetary medium variability has been extensively studied by means of different approaches showing the existence of a wide variety of dynamical features, such as self-similarity, self-organization, turbulence and intermittency, and so on. Recently, by means of Parker solar probe measurements, it has been found that solar wind magnetic field fluctuations in the inertial range show a clear transition near 0.4 AU, both in terms of spectral features and multifractal properties. This breakdown of the scaling features has been interpreted as the evidence of a dynamical phase transition. Here, by using the Klimontovich S-theorem, we investigate how the process of self-organization is under way through the inner heliosphere, going deeper into the characterization of this dynamical phase transition by measuring the evolution of entropic-based measures through the inner heliosphere.

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Verheest, F., M. Vandas, B. Buti, N. F. Cramer, M. Dryer, S. R. Habbal, J. V. Hollweg, M. C. E. Huber, M. Kojima et H. Ripken. « Commission 49 : Interplanetary Plasma and Heliosphere : (Plasma Interplanetaire et Heliosphere) ». Transactions of the International Astronomical Union 24, n^o 1 (2000) : 77–84. http://dx.doi.org/10.1017/s0251107x00002625.

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In the last decade the triennial reports from Commission 49 have covered various topics like (nonlinear) plasma processes, magnetohydrodynamic phenomena and flows in the heliosphere, solar wind composition, transient events in, and latitudinal dependencies of, the heliosphere, interstellar gas flow through the interface region, kinetic versus magnetohydrodynamic theory in heliospheric plasmas and charged dust in space plasmas. Continuing the tradition of summarizing specific aspects to give astronomers outside our own specialty a flavour of our field, we now address recent advances in understanding coronal mass ejections in interplanetary space and the inner heliospheric solar wind under quiet and perturbed conditions. We owe a great debt of gratitude to the eminent contributors for their valiant efforts in writing these succinct but clear reports and guiding us through the recent literature.

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Ruiz, M. E., S. Dasso, W. H. Matthaeus, E. Marsch et J. M. Weygand. « Dynamical evolution of anisotropies of the solar wind magnetic turbulent outer scale ». Proceedings of the International Astronomical Union 7, S286 (octobre 2011) : 164–67. http://dx.doi.org/10.1017/s1743921312004796.

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AbstractThe evolution of the turbulent properties in the solar wind, during the travel of the parcels of fluid from the Sun to the outer heliosphere still has several unanswered questions. In this work, we will present results of an study on the dynamical evolution of turbulent magnetic fluctuations in the inner heliosphere. We focused on the anisotropy of the turbulence integral scale, measured parallel and perpendicular to the direction of the local mean magnetic field, and study its evolution according to the aging of the plasma parcels observed at different heliodistances. As diagnostic tool we employed single-spacecraft correlation functions computed with observations collected by Helios 1 & 2 probes over nearly one solar cycle. Our results are consistent with driving modes with wave-vectors parallel to the direction of the local mean magnetic field near the Sun, and a progressive spectral transfer of energy to modes with perpendicular wave-vectors. Advances made in this direction, as those presented here, will contribute to our understanding of the magnetohydrodynamical turbulence and Alfvénic-wave activity for this system, and will provide a quantitative input for models of charged solar and galactic energetic particles propagation and diffusion throughout the inner heliosphere.

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Marquardt, J., B. Heber, M. S. Potgieter et R. D. Strauss. « Energy spectra of carbon and oxygen with HELIOS E6 ». Astronomy & ; Astrophysics 610 (février 2018) : A42. http://dx.doi.org/10.1051/0004-6361/201731490.

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Context. Anomalous cosmic rays (ACRs) are well-suited to probe the transport conditions of cosmic rays in the inner heliosphere. We revisit the HELIOS data not only in view of the upcoming Solar Orbiter experiment but also to put constraints on particle transport models in order to provide new insight into the boundary conditions close to the Sun. Aims. We present here the energy spectra of galactic cosmic ray (GCR) carbon and oxygen, as well as of ACR oxygen during solar quiet time periods between 1975 to 1977, utilizing both HELIOS spacecraft at distances between ~0.3 and 1 AU. The radial gradient (Gr ≈ 50%/AU) of 9–28.5 MeV ACR oxygen in the inner heliosphere is about three times larger than the one determined between 1 and 10 AU by utilizing the Pioneer 10 measurements. Methods. The chemical composition as well as the energy spectra have been derived by applying the dE∕dx − E-method. In order to derive these values, special characteristics of the instrument have been taken into account. Results. A good agreement of the GCR energy spectra of carbon and oxygen measured by the HELIOS E6 instrument between 0.3 and 1 AU and the Interplanetary Monitoring Platform (IMP) 8 at 1 AU was found. For ACR oxygen, we determined a radial gradient of about 50%/AU that is three times larger than the one between 7 and 14 AU, indicating a strong change in the inner heliosphere.

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Messerotti, Mauro. « Defining and Characterising Heliospheric Weather and Climate ». Proceedings of the International Astronomical Union 13, S335 (juillet 2017) : 226–31. http://dx.doi.org/10.1017/s1743921317008857.

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AbstractAt large distance scales, space exploration in the last decades has significantly helped in better locating the boundaries of the Heliosphere and outlining its shape as well as in probing the various plasma domains that separate the inner heliospheric region from the interstellar one. At shorter distance scales, a fleet of spacecraft has been probing the outer and inner Solar System plasma with a high level of detail.This monitoring, complemented by space- and ground-based observations of processes relevant to the Heliosphere, has pointed out a series both of intrinsic and extrinsic perturbations that characterise the physical state of heliospheric plasmas both at small and large spatial scales and on short and long temporal scales.By means of concept maps that schematise the association among concepts, in this work we will present a new domain ontology for the definition and characterisation of Heliospheric Weather and Climate.

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Martinović, Mihailo M., Kristopher G. Klein, Tereza Ďurovcová et Benjamin L. Alterman. « Ion-driven Instabilities in the Inner Heliosphere. I. Statistical Trends ». Astrophysical Journal 923, n^o 1 (1 décembre 2021) : 116. http://dx.doi.org/10.3847/1538-4357/ac3081.

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Abstract Instabilities described by linear theory characterize an important form of wave–particle interaction in the solar wind. We diagnose unstable behavior of solar wind plasma between 0.3 and 1 au via the Nyquist criterion, applying it to fits of ∼1.5M proton and α particle Velocity Distribution Functions (VDFs) observed by Helios I and II. The variation of the fraction of unstable intervals with radial distance from the Sun is linear, signaling a gradual decline in the activity of unstable modes. When calculated as functions of the solar wind velocity and Coulomb number, we obtain more extreme, exponential trends in the regions where collisions appear to have a notable influence on the VDF. Instability growth rates demonstrate similar behavior, and significantly decrease with Coulomb number. We find that for a nonnegligible fraction of observations, the proton beam or secondary component might not be detected, due to instrument resolution limitations, and demonstrate that the impact of this issue does not affect the main conclusions of this work.

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Adhikari, L., G. P. Zank, L. L. Zhao et D. Telloni. « 2D and Slab Turbulent Cascade Rates in the Inner Heliosphere ». Astrophysical Journal 938, n^o 2 (1 octobre 2022) : 120. http://dx.doi.org/10.3847/1538-4357/ac9234.

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Abstract We present a theoretical and observational study of 2D and slab turbulence cascade (or heating) rates of transverse total turbulence energies, transverse cross helicity, transverse outward and inward Elsässer energy, transverse fluctuating magnetic energy density, and transverse fluctuating kinetic energy from the perihelion of the first Parker Solar Probe (PSP) orbit at ∼36.6 R ⊙ to Solar Orbiter (SolO) at ∼177 R ⊙. We use the Adhikari et al. (2021a) approach to calculate the observed transverse turbulence heating rate, and the nearly incompressible magnetohydrodynamic (NI MHD) turbulence transport theory to calculate the theoretical turbulence cascade rate. We find from the 1 day long PSP measurements at 66.5 R ⊙, and the SolO measurements at 176.3 R ⊙ that various transverse turbulent cascade rates increase with increasing angle, from 10° to 98°, between the mean solar wind speed and mean magnetic field (θ UB), indicating that the 2D heating rate is largest in the inner heliosphere. Similarly, we find from the theoretical and observed results that the 2D heating rate is larger than the slab heating rate as a function of heliocentric distance. We present a comparison between the theoretical and observed 2D and slab turbulence cascade rates as a function of heliocentric distance.

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Stansby, D., T. S. Horbury et L. Matteini. « Diagnosing solar wind origins usingin situmeasurements in the inner heliosphere ». Monthly Notices of the Royal Astronomical Society 482, n^o 2 (22 octobre 2018) : 1706–14. http://dx.doi.org/10.1093/mnras/sty2814.

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