Oxygen flux in the solar wind: Ulysses observations

Steiger, R. von; Zurbuchen, T. H.; McComas, D. J.

doi:10.1029/2010gl045389

Cited by 55 publications

(41 citation statements)

References 34 publications

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“…This introduces an uncertainty of a factor of 1.5 in the absolute value of the DEM. It is interesting to note that a comparison of the value of the sulfur FIP bias determined here with the values reviewed by Schmelz et al (2012) shows a large uncertainty: the value ranging between 1.0 and 1.5 found in our measurements is in agreement with the values determined in solar energetic particles and corotating interacting regions (Reames 1995) and in solar flares by Phillips et al (2003), but disagrees with solar wind measurements (von Steiger et al 2000(von Steiger et al , 2010 and the spectroscopic measurements of Fludra & Schmelz (1999).…”

Section: Element Compositionsupporting

confidence: 64%

Hot Plasma Associated With a Coronal Mass Ejection

Landi

Miralles

Raymond

et al. 2013

ApJ

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We analyze coordinated observations from the EUV Imaging Spectrometer (EIS) and X-Ray Telescope (XRT) on board Hinode of an X-ray Plasma Ejection (XPE) that occurred during the coronal mass ejection (CME) event of 2008 April 9. The XPE was trailing the CME core from behind, following the same trajectory, and could be identified both in EIS and XRT observations. Using the EIS spectrometer, we have determined the XPE plasma parameters, measuring the electron density, thermal distribution, and elemental composition. We have found that the XPE composition and electron density were very similar to those of the pre-event active region plasma. The XPE temperature was higher, and its thermal distribution peaked at around 3 MK; also, typical flare lines were absent from EIS spectra, indicating that any XPE component with temperatures in excess of 5 MK was likely either faint or absent. We used XRT data to investigate the presence of hotter plasma components in the XPE that could have gone undetected by EIS and found that-if at all present-these components have small emission measure values and their temperature is in the 8-12.5 MK range. The very hot plasma found in earlier XPE observations obtained by Yohkoh seems to be largely absent in this CME, although plasma ionization timescales may lead to non-equilibrium ionization effects that could make bright lines from ions formed in a 10 MK plasma not detectable by EIS. Our results supersede the XPE findings of Landi et al., who studied the same event with older response functions for the XRT Al-poly filter; the differences in the results stress the importance of using accurate filter response functions.

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Section: Element Compositionsupporting

confidence: 64%

Hot Plasma Associated With a Coronal Mass Ejection

Landi

Miralles

Raymond

et al. 2013

ApJ

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“…Sulfur, on the other hand, might need to be lowered to ∼65% of its current value. The lower sulfur abundance is consistent with the spectroscopic measurements from Veck & Parkinson (1981) and Fludra & Schmelz (1999), but at odds with the SEP data from Reames (1995) and the solar wind data from von Steiger et al (2000Steiger et al ( , 2010. Abundance results for this intermediate-FIP element are difficult to pin down, and further analysis will be required to sort out this problem.…”

Section: Fip Effectsupporting

confidence: 57%

“…Spectroscopic , SEP (Reames 1995), and solar wind (von Steiger et al 2000(von Steiger et al , 2010 data suggest that the coronal-to-photospheric abundance ratios of elements with low first ionization potential (FIP < 10 eV) seem to be enhanced relative to those with high FIP (>11 eV). This fractionation probably results from a separation of ions and neutrals.…”

Section: Introductionmentioning

confidence: 99%

Deriving Plasma Densities and Elemental Abundances From Serts Differential Emission Measure Analysis

Schmelz

Kimble

Saba

2012

ApJ

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We use high-resolution spectral emission line data obtained by the SERTS instrument during three rocket flights to demonstrate a new approach for constraining electron densities of solar active region plasma. We apply differential emission measure (DEM) forward-fitting techniques to characterize the multithermal solar plasma producing the observed EUV spectra, with constraints on the high-temperature plasma from the Yohkoh Soft X-ray Telescope. In this iterative process, we compare line intensities predicted by an input source distribution to observed line intensities for multiple iron ion species, and search a broad range of densities to optimize χ 2 simultaneously for the many available density-sensitive lines. This produces a density weighted by the DEM, which appears to be useful for characterizing the bulk of the emitting plasma over a significant range of temperature. This "DEM-weighted density" technique is complementary to the use of density-sensitive line ratios and less affected by uncertainties in atomic data and ionization fraction for any specific line. Once the DEM shape and the DEM-weighted density have been established from the iron lines, the relative elemental abundances can be determined for other lines in the spectrum. We have also identified spectral lines in the SERTS wavelength range that may be problematic.

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“…The values in this plot almost exactly duplicate those published by Geiss for a polar coronal hole fast wind stream. Clearly, the species of Iron, Magnesium, and Silicon are overabundant in the fast solar wind (relative to the photosphere) and thus the process heating (and launching) the material must intrinsically imprint this fractionation on the outflowing material, as has been suggested in the literature (e.g., Geiss 1998; von Steiger et al 2010). The correspondence between these values and those of Geiss et al (1995) would appear to indicate that the basal composition of the fast solar wind is relatively invariant, but the strength and distribution of magnetic field in the polar and equatorial coronal hole sources of the streams under consideration are likely to be approximately the same.…”

Section: Composition Measurements As Diagnostics Of Fsw Footprint Heamentioning

confidence: 97%

Recent Observations of Plasma and Alfvénic Wave Energy Injection at the Base of the Fast Solar Wind

McIntosh

2012

Space Sci Rev

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We take stock of recent observations that identify the episodic plasma heating and injection of Alfvénic energy at the base of fast solar wind (in coronal holes). The plasma heating is associated with the occurrence of chromospheric spicules that leave the lower solar atmosphere at speeds of order 100km/s, the hotter coronal counterpart of the spicule emits radiation characteristic of root heating that rapidly reaches temperatures of the order of 1MK. Furthermore, the same spicules and their coronal counterparts ("Propagating Coronal Disturbances"; PCD) exhibit large amplitude, high speed, Alfvénic (transverse) motion of sufficient energy content to accelerate the material to high speeds. We propose that these (disjointed) heating and accelerating components form a one-two punch to supply, and then accelerate, the fast solar wind. We consider some compositional constraints on this concept, extend the premise to the slow solar wind, and identify future avenues of exploration.

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Oxygen flux in the solar wind: Ulysses observations

Cited by 55 publications

References 34 publications

Hot Plasma Associated With a Coronal Mass Ejection

Hot Plasma Associated With a Coronal Mass Ejection

Deriving Plasma Densities and Elemental Abundances From Serts Differential Emission Measure Analysis

Recent Observations of Plasma and Alfvénic Wave Energy Injection at the Base of the Fast Solar Wind

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