Composition of quasi‐stationary solar wind flows from Ulysses/Solar Wind Ion Composition Spectrometer

Steiger, R. von; Schwadron, N. A.; Fisk, L. A.; Geiss, J.; Gloeckler, G.; Hefti, S.; Wilken, B.; Wimmer-Schweingruber, R; Zurbuchen, T. H.

doi:10.1029/1999ja000358

Cited by 488 publications

(446 citation statements)

References 48 publications

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“…Although one can see significant deviations, especially for O + , former studies claimed that the inner-source PUI composition resembles the elemental solar-wind composition that is shown in Table 4 taken from von Steiger et al (2000), except for the neon abundance that was taken from the more recent analysis of Shearer et al (2014). Our results confirm these systematic deviations and raise the question of their origin, which is probably connected to the production mechanism of inner-source PUIs.…”

Section: Comparison With Former Resultssupporting

confidence: 78%

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Composition of inner-source heavy pickup ions at 1 AU: SOHO/CELIAS/CTOF observations

Taut

Berger

Drews

et al. 2015

A&A

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Context. Pickup ions in the inner heliosphere mainly originate in two sources, one interstellar and one in the inner solar system. In contrast to the interstellar source that is comparatively well understood, the nature of the inner source has not been clearly identified. Former results obtained with the Solar Wind Ion Composition Spectrometer on-board the Ulysses spacecraft revealed that the composition of inner-source pickup ions is similar, but not equal, to the elemental solar-wind composition. These observations suffered from very low counting statistics of roughly one C + count per day. Aims. Because the composition of inner-source pickup ions could lead to identifying their origin, we used data from the Charge-TimeOf-Flight sensor on-board the Solar and Heliospheric Observatory. It offers a large geometry factor that results in about 100 C + counts per day combined with an excellent mass-per-charge resolution. These features enable a precise determination of the inner-source heavy pickup ion composition at 1 AU. To address the production mechanisms of inner-source pickup ions, we set up a toy model based on the production scenario involving the passage of solar-wind ions through thin dust grains to explain the observed deviations of the inner-source PUI and the elemental solar-wind composition.Methods. An in-flight calibration of the sensor allows identification of heavy pickup ions from pulse height analysis data by their mass-per-charge. A statistical analysis was performed to derive the inner-source heavy pickup ion relative abundances of N + , O + , Ne + , Mg + , Mg 2+ , and Si + compared to C + . Results. Our results for the inner-source pickup ion composition are in good agreement with previous studies and confirm the deviations from the solar-wind composition. The large geometry factor of the Charge-Time-of-Flight sensor even allowed the abundance ratios of the two most prominent pickup ions, C + and O + , to be investigated at varying solar-wind speeds. We found that the O + /C + ratio increases systematically with higher solar-wind speeds. This observation is an unprecedented feature characterising the production of inner-source pickup ions. Comparing our observations to the toy model results, we find that both the deviation from the solar-wind composition and the solar-wind-speed dependent O + /C + ratio can be explained.

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Section: Comparison With Former Resultssupporting

confidence: 78%

“…To quantify Table 4. Comparison of the heavy PUI composition derived from CTOF data with the solar-wind composition (von Steiger et al 2000;Shearer et al 2014) and the modelled composition that one would expect from the production scenario proposed by Wimmer-Schweingruber & Bochsler (2003).…”

Section: Error Estimationmentioning

confidence: 99%

Composition of inner-source heavy pickup ions at 1 AU: SOHO/CELIAS/CTOF observations

Taut

Berger

Drews

et al. 2015

A&A

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“…those lacking a strong dependence on the first ionization potential (FIP) of the elements, as seen in the fast solar wind (e.g. von Steiger et al, 2000). SEPs show a fairly strong dependence on FIP (Reames, 1995(Reames, , 2014(Reames, , 2015 in the average abundances that serve as a reference for all of the events we study.…”

Section: Nanojets?mentioning

confidence: 99%

The Origin of Element Abundance Variations in Solar Energetic Particles

Reames

2016

Sol Phys

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Abundance enhancements, during acceleration and transport in both gradual and impulsive solar energetic particle (SEP) events, vary approximately as power laws in the mass-to-charge ratio [A/Q] of the ions. Since the Q-values depend upon the electron temperature of the source plasma, this has allowed a determination of this temperature from the pattern of element-abundance enhancements and a verification of the expected inverse-time dependence of the power of A/Q for diffusive transport of ions from the SEP events, with scattering mean free paths found to be between 0.2 and 1 AU. SEP events derived from plasma of different temperatures map into different regions in typical crossplots of abundances, spreading the distributions. In comparisons of SEP events with temperatures above 2 MK, impulsive events show much broader non-thermal variation of abundances than do gradual events. The extensive shock waves accelerating ions in gradual events may average over much of an active region where numerous but smaller magnetic reconnections, "nanojets", produce suprathermal seed ions, thus averaging over varying abundances, while an impulsive SEP event only samples one local region of abundance variations. Evidence for a reference He/O abundance ratio of 91, rather than 57, is also found for the hotter plasma. However, while this is similar to the solar-wind abundance of He/O, the solar-wind abundances otherwise provide an unacceptably poor reference for the SEP abundance enhancements, generating extremely large errors.

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“…The fast wind [V ≥ 600 km s −1 ] is believed to originate in coronal holes and exhibits a composition characteristic of the photosphere with charge states that indicate temperatures in the 0.8 MK to 1.0 MK range (von Steiger et al, 2000). The origins of the slow wind [V ≈ 400 km s −1 ] remain controversial.…”

Section: Introductionmentioning

confidence: 99%

Tracking Solar Active Region Outflow Plasma from Its Source to the Near-Earth Environment

Culhane¹,

Brooks

Driel-Gesztelyi

et al. 2014

Sol Phys

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Seeking to establish whether active-region upflow material contributes to the slow solar wind, we examine in detail the plasma upflows from Active Region (AR) 10978, which crossed the Sun's disc in the interval 8 to 16 December 2007 during Carrington rotation (CR) 2064. In previous work, using data from the Hinode/EUV Imaging Spectrometer, upflow velocity evolution was extensively studied as the region crossed the disc, while a linear forcefree-field magnetic extrapolation was used to confirm aspects of the velocity evolution and to establish the presence of quasi-separatrix layers at the upflow source areas. The plasma properties, temperature, density, and first ionisation potential bias [FIP-bias] were measured with the spectrometer during the disc passage of the active region. Global potential-field source-surface (PFSS) models showed that AR 10978 was completely covered by the closed field of a helmet streamer that is part of the streamer belt. Therefore it is not clear how any of the upflowing AR-associated plasma could reach the source surface at 2.5 R and contribute to the slow solar wind. However, a detailed examination of solar-wind in-situ data obtained by the Advanced Composition Explorer (ACE) spacecraft at the L 1 point shows that increases in O 7+ /O 6+ , C 6+ /C 5+ , and Fe/O -a FIP-bias proxy -are present before the heliospheric current-sheet crossing. These increases, along with an accompanying reduction in proton velocity and an increase in density are characteristic of both AR and slow-solarwind plasma. Finally, we describe a two-step reconnection process by which some of the upflowing plasma from the AR might reach the heliosphere.

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Composition of quasi‐stationary solar wind flows from Ulysses/Solar Wind Ion Composition Spectrometer

Cited by 488 publications

References 48 publications

Composition of inner-source heavy pickup ions at 1 AU: SOHO/CELIAS/CTOF observations

Composition of inner-source heavy pickup ions at 1 AU: SOHO/CELIAS/CTOF observations

The Origin of Element Abundance Variations in Solar Energetic Particles

Tracking Solar Active Region Outflow Plasma from Its Source to the Near-Earth Environment

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