Kinetic properties of solar wind minor ions and protons measured with SOHO/CELIAS

Hefti, S.; Grünwaldt, H.; Ipavich, F. M.; Bochsler, P.; Hovestadt, D.; Aellig, M. R.; Hilchenbach, M.; Kallenbach, R.; Galvin, A. B.; Geiss, J.; Gliem, F.; Gloeckler, G.; Klecker, B.; Marsch, E.; Möbius, E.; Neugebauer, M.; Würz, Peter

doi:10.1029/1998ja900022

Cited by 67 publications

(61 citation statements)

References 13 publications

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“…This is in qualitative agreement with the result described by Zurbuchen et al [2000] for SWICS data around 2.5 AU and SOHO-CELIAS data at 1 AU [Hefti et al, 1998]. A quantitative comparison of the results in these papers shows that the trend is decreasing with increasing distance from the Sun.…”

Section: Observationssupporting

confidence: 92%

Kinetic properties of heavy solar wind ions from Ulysses-SWICS

Steiger

Zurbuchen

2002

Advances in Space Research

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[1] The kinetic properties of heavy ions in the solar wind reflect the plasma processes governing the solar wind in the heliosphere. We use Ulysses-SWICS data that resolve heavy ions in a wide range of mass-per-charge values, 2 m/q 9.33, to investigate the heavy ions and their dynamic evolution throughout the heliosphere. While at 1 AU the imprint of Coulomb collisions is known to be present in the slow solar wind, we show that is vanishes by the time the wind has reached 5 AU. All ion species flow with equal bulk and thermal speeds there. This is interpreted as a progressive dominance of wave-particle interactions over Coulomb collisions. Citation: von Steiger, R., and T. H.

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Section: Observationssupporting

confidence: 92%

Kinetic properties of heavy solar wind ions from Ulysses-SWICS

Steiger

Zurbuchen

2002

Advances in Space Research

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“…Later, several other studies focusing on bulk speeds of heavy ions have been carried out with different instruments on different spacecraft, i.e., with the Ion Composition Instrument (ICI) on ISEE-3 (Ogilvie et al 1980a, Schmid et al 1987, Bochsler 1989, with SWICS on Ulysses , and with CELIAS on SOHO . As others had shown previously, the work of Hefti et al (1998) demonstrated that heavy ions tend to travel significantly faster in the fast solar wind, whereas they show no significant deviation from proton speeds in slow solar wind. This is illustrated in Fig.…”

Section: Minor Species In the Solar Coronasupporting

confidence: 65%

“…In addition, stream-stream interactions must have considerably smeared out features by the time they arrived at Ulysses, whereas they are still clearly visible at 1 AU. During a period of a full year the helium speed hardly It is evident that in the case of low speeds the observations match this line, whereas in the case of high-speed solar wind significant differences of the order of 20-40 km/s are observed (from Hefti et al 1998) dropped to values below 400 km/s at the Ulysses orbit, despite the fact that periods with the typical compositional characteristics of low-speed solar wind have been included in the observations. This demonstrates impressively that kinetic properties of minor species in the solar wind are much less conservative properties than compositional signatures.…”

Section: Minor Species In the Solar Coronamentioning

confidence: 75%

Minor ions in the solar wind

Bochsler

2006

Astron Astrophys Rev

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Ions heavier than 4 He are treated as "minors" in the solar wind. This is justified for many applications since minor ions have no significant influence on the dynamics of the interplanetary plasma. However, minor ions carry information on many aspects of the formation, on the acceleration and on the transfer of solar plasma from the corona into the interplanetary space. This review concentrates on various aspects of minor ions as diagnostic tracers. The elemental abundance patterns of the solar wind are shaped in the chromosphere and in the lower transition region by processes, which are not fully understood at this moment. Despite this lack of detailed understanding, observed abundance patterns have been classified and are now commonly used to characterize the sources, and to trace back solar-wind flows to their origins in the solar atmosphere. Furthermore, the solar wind is the most important source of information for solar isotopic abundances and for solar abundances of volatile elements. In order to fully exploit this information, a comprehensive understanding of elemental and isotopic fractionation processes is required. We provide observational clues to distinguish different processes at work.

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“…It is well known that heavy ions in the solar wind have approximately the same bulk speed and the same thermal speed (i.e., approximately a mass-proportional temperature). That is particularly true at large heliocentric distances where the heliospheric magnetic field is likely to be perpendicular to the radial direction and, due to the negligible cross-field transport of thermal particles, all heavies are expected to have the same radial speed as measured by SWICS [Hefti et al, 1998;von Steiger and Zurbuchen, 2006]. Misidentifications are reliably identified as significant deviations from these scaling Figure A2.…”

Section: Von Steiger and Zurbuchen: Polar Coronal Holes A01105 A01105mentioning

confidence: 97%

Polar coronal holes during the past solar cycle: Ulysses observations

Steiger

Zurbuchen

2011

J. Geophys. Res.

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[1] During its nearly 19-year mission, Ulysses pioneered novel measurements of the three-dimensional heliosphere and particularly in situ observations of high-latitude solar wind from polar coronal holes (PCHs). Winds from PCHs exhibit constant elemental abundances to within the limits of the measurements, indicative of the fact that such winds truly provide a ground state of solar wind composition. However, these solar wind streams show long-term variability in the composition of ionic charge states frozen into the low corona. The C and O freeze-in temperatures measured in high-latitude solar wind have decreased ∼10% as compared to the previous solar minimum and are now around 0.87 and 1.01 MK, respectively. The ionization states of Si and Fe also exhibit a substantial cooling with a reduction of 0.4 and 0.5 charge states, respectively. We show that these observations are indicative of an overall decrease of coronal temperature, forming a trend toward cooler PCH temperature persisting for over 14 years. We support these observations with a detailed and comprehensive description of the data analysis processes relevant for Ulysses SWICS and similar instruments.Citation: von Steiger, R., and T. H. Zurbuchen (2011), Polar coronal holes during the past solar cycle: Ulysses observations,

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Kinetic properties of solar wind minor ions and protons measured with SOHO/CELIAS

Cited by 67 publications

References 13 publications

Kinetic properties of heavy solar wind ions from Ulysses-SWICS

Kinetic properties of heavy solar wind ions from Ulysses-SWICS

Minor ions in the solar wind

Polar coronal holes during the past solar cycle: Ulysses observations

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