UVCS/[ITAL]SOHO[/ITAL] Empirical Determinations of Anisotropic Velocity Distributions in the Solar Corona

Kohl, J. L.; Noci, G.; Antonucci, E.; Tondello, G.; Huber, M. C. E.; Cranmer, Steven R.; Strachan, L.; Panasyuk, A. V.; Gardner, L. D.; Romoli, M.; Fineschi, Silvano; Dobrzycka, D.; Raymond, J. C.; Nicolosi, P.; Siegmund, O. H. W.; Spadaro, D.; Benna, C.; Ciaravella, A.; Giordano, S.; Habbal, Shadia Rifai; Karovska, M.; Li, X.; Martin, R.; Michels, J.; Modigliani, A.; Naletto, G.; O'Neal, Ray H.; Pernechele, Claudio; Poletto, G.; Smith, P. L.; Suleiman, R. M.

doi:10.1086/311434

Cited by 395 publications

(251 citation statements)

References 31 publications

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“…The model predicts CH plasma to reach 764 km s -1 at 1 AU (with the sonic point at 2.3 ⊙ ), while the dense structure plasma reaches at 1 AU a lower speed of 590 km s -1 (with sonic point at 3.4 ⊙ and a speed lower than the CH plasma speed throughout the corona). This model yields higher proton than electron temperatures in the inner corona, a possibility that has been ignored by previous authors, but it is consistent with spectroscopic measurements that suggest is lower than proton temperatures (e.g., Kohl et al, 1996Kohl et al, , 1998 in CH plasmas. However, Habbal et al (1995) results cannot be blindly applied to plumes, because the dense structures imaged by the coronagraphs have not been unambiguously associated with plumes, but, possibly, with CH boundaries.…”

Section: Empirical Modelssupporting

confidence: 88%

Solar Coronal Plumes

Poletto

2015

Living Rev. Sol. Phys.

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Polar plumes are thin long ray-like structures that project beyond the limb of the Sun polar regions, maintaining their identity over distances of several solar radii. Plumes have been first observed in white-light (WL) images of the Sun, but, with the advent of the space era, they have been identified also in X-ray and UV wavelengths (XUV) and, possibly, even in in situ data. This review traces the history of plumes, from the time they have been first imaged, to the complex means by which nowadays we attempt to reconstruct their 3-D structure. Spectroscopic techniques allowed us also to infer the physical parameters of plumes and estimate their electron and kinetic temperatures and their densities. However, perhaps the most interesting problem we need to solve is the role they cover in the solar wind origin and acceleration: Does the solar wind emanate from plumes or from the ambient coronal hole wherein they are embedded? Do plumes have a role in solar wind acceleration and mass loading? Answers to these questions are still somewhat ambiguous and theoretical modeling does not provide definite answers either. Recent data, with an unprecedented high spatial and temporal resolution, provide new information on the fine structure of plumes, their temporal evolution and relationship with other transient phenomena that may shed further light on these elusive features. Article RevisionsLiving Reviews supports two ways of keeping its articles up-to-date:Fast-track revision. A fast-track revision provides the author with the opportunity to add short notices of current research results, trends and developments, or important publications to the article. A fast-track revision is refereed by the responsible subject editor. If an article has undergone a fast-track revision, a summary of changes will be listed here.Major update. A major update will include substantial changes and additions and is subject to full external refereeing. It is published with a new publication number.For detailed documentation of an article's evolution, please refer to the history document of the article's online version at http://dx

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Section: Empirical Modelssupporting

confidence: 88%

Solar Coronal Plumes

Poletto

2015

Living Rev. Sol. Phys.

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“…The models were able to produce reasonable parameters for the corona and wind, in compliance with basic observations of the effective wave amplitude as derived from the line width of extreme ultraviolet radiation lines ) that are emitted by heavy ions in the solar transition region. Tu & Marsch (2001) have further used the high-frequency wave-energysweeping mechanism of the previous models to explain also why the O +5 line widths indicate strong perpendicular ion heating (Kohl et al 1998).…”

Section: Introductionmentioning

confidence: 99%

“…Because the resonant damping rate of the waves is very high, the ions with a low resonance frequency may absorb most of the energy in a short time, and then little is left for protons. However, SOHO observations (Kohl et al 1998) showed that both O 5+ ions and protons are heated, and that heating is indeed needed to explain the widths of EUV emission lines (Wilhem et al 1998). To avoid the problem mentioned above, and suggested a two-step process yielding sizable heating of both O +5 and protons.…”

Section: Introductionmentioning

confidence: 99%

Wave dissipation by ion cyclotron resonance in the solar corona

Marsch

2001

A&A

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Abstract. It has recently been suggested that small-scale reconnection occurring in the chromospheric network creates high-frequency Alfvén waves, and that these waves may represent the main energy source for the heating of the solar corona and generation of the solar wind. However, if these waves exist, they will be absorbed preferentially by the minor heavy ions with low gyrofrequencies, and thus it is unclear whether there is actually enough wave energy left over for the heating and acceleration of the major solar wind ions, namely protons and alpha particles, in the extended corona after the absorption by heavy ions (Cranmer 2000). We have studied this problem with the multi-fluid model presented by Tu & Marsch (2001), which includes the self-consistent treatment of the damping of the waves as well as the associated acceleration and heating of the ions. We found that if the wave power density is sufficiently large, say about 1000 nT 2 Hz −1 at 160 Hz and 2.5 R , then the wave absorption by a prominent minor ion such as O +5 is small, and most of the wave energy is left for absorption by protons. This occurs because the minor ions are quickly (within several gyroperiods) accelerated and then are induced to partially surfing the waves. However, if the wave power is too low, say lower than 10 nT 2 Hz −1 at 160 Hz and 2.5 R , then the damping of the wave power by the O +5 ions is severe, and little wave energy is left for protons.

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“…In situ measurements of the fast solar wind and remote sensing observations of the solar corona have revealed that the heavy minor ions are faster and hotter than the protons, and they generally are preferentially heated in the perpendicular direction (Feldman et al 1974;Marsch et al 1982;Kohl et al 1998;Li et al 1998;von Steiger & Zurbuchen 2006;Marsch 2006). Although the physical mechanisms responsible for the observed ion behavior are still in debate, it is commonly believed that the dissipation of Alfvén waves may be relevant to the observed ion heating.…”

Section: Conclusion and Discussionmentioning

confidence: 99%

Ion Dynamics During the Parametric Instabilities of a Left-Hand Polarized Alfvén Wave in a Proton-Electron-Alpha Plasma

Gao

et al. 2013

ApJ

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The parametric instabilities of an Alfvén wave in a proton-electron plasma system are found to have great influence on proton dynamics, where part of the protons can be accelerated through the Landau resonance with the excited ion acoustic waves, and a beam component along the background magnetic field is formed. In this paper, with a onedimensional hybrid simulation model, we investigate the evolution of the parametric instabilities of a monochromatic left-hand polarized Alfvén wave in a proton-electron-alpha plasma with a low beta. When the drift velocity between the protons and alpha particles is sufficiently large, the wave numbers of the backward daughter Alfvén waves can be cascaded toward higher values due to the modulational instability during the nonlinear evolution of the parametric instabilities, and the alpha particles are resonantly heated in both the parallel and perpendicular direction by the backward waves. On the other hand, when the drift velocity of alpha particles is small, the alpha particles are heated in the linear growth stage of the parametric instabilities due to the Landau resonance with the excited ion acoustic waves. Therefore, the heating occurs only in the parallel direction, and there is no obvious heating in the perpendicular direction. The relevance of our results to the preferential heating of heavy ions observed in the solar wind within 0.3 AU is also discussed in this paper.

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UVCS/[ITAL]SOHO[/ITAL] Empirical Determinations of Anisotropic Velocity Distributions in the Solar Corona

Cited by 395 publications

References 31 publications

Solar Coronal Plumes

Solar Coronal Plumes

Wave dissipation by ion cyclotron resonance in the solar corona

Ion Dynamics During the Parametric Instabilities of a Left-Hand Polarized Alfvén Wave in a Proton-Electron-Alpha Plasma

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