Neon‐20, oxygen‐16, and helium‐4 densities, temperatures, and suprathermal tails in the solar wind determined with WIND/MASS

Collier, M. R.; Hamilton, D. C.; Gloeckler, G.; Bochsler, P.; Sheldon, Robert B.

doi:10.1029/96gl00621

Cited by 183 publications

(124 citation statements)

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“…Their value is possibly somewhat biased towards abundances in low-speed solar wind. Collier et al (1996) obtained similar values with WIND/MASS for in-ecliptic solar wind for a period of relatively low solar activity from December 1994 through August 1995. They find [Ne/O] = 0.14 ± 0.01 and no significant dependence of this ratio from the solar wind speed.…”

Section: H I Given Insupporting

confidence: 68%

“…Relating the oxygen abundance of the solar wind to the helium abundance gives a consistent picture: Bochsler et al (1986) find [He/O] = 75 ± 20, whereas Collier et al (1996) find [He/O] = 70 ± 6. The averages of Collier et al (1996) are shown in Fig.…”

Section: H I Given Inmentioning

confidence: 66%

“…Note again that shape and slope of this curve are unambiguously determined by the Coulomb-drag factors given in Table 1 and not derived from the fit to the data. Collier et al (1996). The dashed line is a fit with the Coulomb drag model of Bodmer & Bochsler (1998).…”

Section: H I Given Inmentioning

confidence: 99%

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Solar abundances of oxygen and neon derived from solar wind observations

Bochsler¹

2007

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Context. Recently, a revision of the solar abundances of C, N, and O to substantially lower values has led to a controversy on solar opacities in the solar standard model and to the suggestion to revise the solar abundance of neon upward by as much as a factor of 1.6 leading to enhanced solar neon/oxygen abundance ratios by a factor of 3. Neon and oxygen are neighboring elements with easily defined charged states in the solar wind, and they have been well identified and measured for over two decades in the solar wind under many circumstances and with several instruments. The solar wind Ne/O ratio is 0.14 with a conservative error estimate of ±0.03, consistent with the coronal value derived from solar energetic particle measurements. Aims. We investigate, whether solar wind observations are consistent with the newly proposed elemental solar abundances of neon and oxygen. Methods. The solar helium abundance has been derived from helioseismological observations. Helium and neon abundances in the solar wind have been well determined with the Apollo Foil experiments and, more recently, confirmed with the Genesis sample return mission. With these observations and the neon/oxygen solar wind abundance ratio determined by in-situ mass-spectrometry and using a simple theoretical model of Coulomb-drag fractionation for the solar wind, we estimate solar abundances for neon and oxygen. Results. From the variability of the helium/oxygen and the helium/neon ratio in the solar wind and from theoretical considerations, we conclude that the helium/neon ratio in the outer solar convective zone is 900 ± 110. Our best estimates of the solar neon and oxygen abundances in logarithmic dex-units are [Ne] = 7.96 ± 0.13, and [O] = 8.87 ± 0.11. Conclusions. Our solar neon/oxygen abundance ratio is consistent with the ratio derived from EUV-spectra from SOHO/CDS. However, our absolute abundance for oxygen is only marginally compatible with the newly derived value for oxygen, and our neon value is clearly incompatible with the recently proposed enhancement of the solar neon abundance.

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Section: H I Given Insupporting

confidence: 68%

Section: H I Given Inmentioning

confidence: 66%

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Solar abundances of oxygen and neon derived from solar wind observations

Bochsler¹

2007

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“…2c). The power-law tails at high-energy parts of ion spectra in space plasmas are long known (Montgomery et al 1968;Collier et al 1996), the powerlaw exponent of ∼ −5 is often detected in ion velocity distribution in space (Gloeckler 2003). During our simulation such tail is formed only for a narrow range of velocities (Fig.…”

Section: Evolutionmentioning

confidence: 98%

Role of Z-pinches in magnetic reconnection in space plasmas

2014

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A widely accepted scenario of magnetic reconnection in collisionless space plasmas is the breakage of magnetic field lines in X-points. In laboratory, reconnection is commonly studied in pinches, current channels embedded into twisted magnetic fields. No model of magnetic reconnection in space plasmas considers both null-points and pinches as peers. We have performed a particle-in-cell simulation of magnetic reconnection in a three-dimensional configuration where null-points are present initially, and Z-pinches are formed during the simulation along the lines of spiral null-points. The non-spiral nullpoints are more stable than spiral ones, and no substantial energy dissipation is associated with them. On the contrary, turbulent magnetic reconnection in the pinches causes the magnetic energy to decay at a rate of ∼ 1.5% per ion gyro period. Dissipation in similar structures is a likely scenario in space plasmas with large fraction of spiral null-points.

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“…Collier et al [1996] fit kappa distributions to both fast and slow solar wind using WIND data. Also using WIND data, Chotoo et al [2000] analyzed power law tails associated with corotating interaction regions and extracted the values of k. The 2004 Voyager 1 termination shock crossing extends suprathermal tail observations into the heliosheath.…”

Section: Introductionmentioning

confidence: 99%

Implications of solar wind suprathermal tails for IBEX ENA images of the heliosheath

et al. 2008

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[1] Decades of interplanetary measurements of the solar wind and other space plasmas have established that the suprathermal ion intensity distributions (j) are non-Maxwellian and are characterized by high-energy power law tails (j $ E Àk ). Recent analysis by Fisk and Gloeckler of suprathermal ion observations between 1-5 AU demonstrates that a particular differential intensity distribution function emerges universally between $2-10 times the solar wind speed with k $ 1.5. This power law tail is particularly apparent in downstream distributions beyond reverse shocks associated with corotating interaction regions. Similar power law tails have been observed in the downstream flow beyond the termination shock by the Low Energy Charged Particle instrument on both Voyager 1 and Voyager 2. Using kappa distributions with internal energy, density, and bulk flow derived from large-scale magnetohydrodynamic models, we calculate the simulated flux of energetic neutral atoms (ENAs) produced in the heliosheath by charge exchange between solar wind protons and interstellar hydrogen. We then produce simulated ENA maps of the heliosheath, such as will be measured by the Interstellar Boundary Explorer Mission (IBEX). We also estimate the expected signal to noise and background ratio for IBEX. The solar wind suprathermal tail significantly increases the ENA flux within the IBEX energy range, $0.01-6 keV, by more than an order of magnitude at the highest energies over the estimates using a Maxwellian. It is therefore essential to consider suprathermal tails in the interpretation of IBEX ENA images and theoretical modeling of the heliospheric termination shock.

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Neon‐20, oxygen‐16, and helium‐4 densities, temperatures, and suprathermal tails in the solar wind determined with WIND/MASS

Cited by 183 publications

References 16 publications

Solar abundances of oxygen and neon derived from solar wind observations

Solar abundances of oxygen and neon derived from solar wind observations

Role of Z-pinches in magnetic reconnection in space plasmas

Implications of solar wind suprathermal tails for IBEX ENA images of the heliosheath

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