Temporal Evolution of Solar Wind Ion Composition and Their Source Coronal Holes During the Declining Phase of Cycle 23. I. Low-Latitude Extension of Polar Coronal Holes

Ko, Y. K.; Muglach, K.; Wang, Yi Ming; Young, Peter R.; Lepri, S. T.

doi:10.1088/0004-637x/787/2/121

Cited by 23 publications

(20 citation statements)

References 51 publications

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“…For instance, as shown in the wind-source identification example in Figure 1, the solar wind streams coming from CH core regions are faster, while the CH boundary streams are slower. Similar results are shown by Neugebauer et al (2002, see Figure 11 in their paper) and Ko et al (2014, Figure 1 in their paper). Several studies have suggested that structures like coronal bright points and plumes which are located in CH boundary regions may also be sources of the SSW (e.g., Madjarska et al 2004;Subramanian et al 2010;Madjarska et al 2012;Fu et al 2014;Karpen et al 2016).…”

Section: +supporting

confidence: 90%

“…Gloeckler et al (2003) suggested that this observational fact supports the notion that the mechanism suggested by the RLO models is the main physical process for heating and acceleration of the nascent solar wind. Our statistical study shows that the anti-correlation between solar wind speeds and O 7+ /O 6+ is not only present for the CH wind (Ko et al 2014) but is also valid for the AR and QS wind. This suggests that the mechanisms which account for the anti-correlation between the solar wind speeds and O 7+ /O 6+ ratio are the same in CH, QS, and AR wind.…”

Section: +supporting

confidence: 50%

“…Case and statistical studies have already shown that CHs are sources of both the fast and slow wind (Neugebauer et al 2002;Ko et al 2014). Woo & Habbal (2000) compared the flow speed derived from Doppler dimming and density observations by UVCS/SoHO (UltraViolet Coronagraph Spectrometer) and suggested that the QS regions are an additional source of the fast solar wind, thus questioning the traditional belief that the fast solar wind originates only from CHs.…”

Section: +mentioning

confidence: 99%

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Charge States and FIP Bias of the Solar Wind from Coronal Holes, Active Regions, and Quiet Sun

Madjarska

Xia

et al. 2017

ApJ

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Connecting in-situ measured solar-wind plasma properties with typical regions on the Sun can provide an effective constraint and test to various solar wind models. We examine the statistical characteristics of the solar wind with an origin in different types of source regions. We find that the speed distribution of coronal hole (CH) wind is bimodal with the slow wind peaking at ∼400 km s −1 and a fast at ∼600 km s −1 . An anti-correlation between the solar wind speeds and the O 7+ /O 6+ ion ratio remains valid in all three types of solar wind as well during the three studied solar cycle activity phases, i.e. solar maximum, decline and minimum. The N F e /N O range and its average values all decrease with the increasing solar wind speed in different types of solar wind. The N F e /N O range (0.06-0.40, FIP bias range 1-7) for AR wind is wider than for CH wind (0.06-0.20, FIP bias range 1-3) while the minimum value of N F e /N O (∼ 0.06) does not change with the variation of speed, and it is similar for all source regions. The two-peak distribution of CH wind and the anti-correlation between the speed and O 7+ /O 6+ in all three types of solar wind can be explained qualitatively by both the waveturbulence-driven (WTD) and reconnection-loop-opening (RLO) models, whereas the distribution features of N F e /N O in different source regions of solar wind can be explained more reasonably by the RLO models.

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Section: +supporting

confidence: 90%

Section: +supporting

confidence: 50%

Section: +mentioning

confidence: 99%

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Charge States and FIP Bias of the Solar Wind from Coronal Holes, Active Regions, and Quiet Sun

Madjarska

Xia

et al. 2017

ApJ

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“…However, boundaries in ionisation state measurements are sometimes observed to be smoothed out at the trailing edge of solar wind streams, in a similar manner to velocity (Schwadron, 2005;Borovsky and Denton, 2016). Ko et al (2014) found O 7+ / O 6+ to be a better tracer of coronal origin than velocity observationally. They report that wind from both the northern and southern polar coronal holes could exhibit the same wind speed but have a notable discrepancy in their corresponding O 7+ / O 6+ values.…”

Section: Introductionmentioning

confidence: 90%

Tests for coronal electron temperature signatures in suprathermal electron populations at 1 AU

2017

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Abstract. The development of knowledge of how the coronal origin of the solar wind affects its in situ properties is one of the keys to understanding the relationship between the Sun and the heliosphere.In this paper, we analyse ACE/SWICS and WIND/3DP data spanning >12 years, and test properties of solar wind suprathermal electron distributions for the presence of signatures of the coronal temperature at their origin which may remain at 1 AU. In particular we re-examine a previous suggestion that these properties correlate with the oxygen charge state ratio O 7+ / O 6+ , an established proxy for coronal electron temperature. We find only a very weak but variable correlation between measures of suprathermal electron energy content and O 7+ / O 6+ . The weak nature of the correlation leads us to conclude, in contrast to earlier results, that an initial relationship with core electron temperature has the possibility to exist in the corona, but that in most cases no strong signatures remain in the suprathermal electron distributions at 1 AU. It cannot yet be confirmed whether this is due to the effects of coronal conditions on the establishment of this relationship or due to the altering of the electron distributions by processing during transport in the solar wind en route to 1 AU. Contrasting results for the halo and strahl population favours the latter interpretation. Confirmation of this will be possible using Solar Orbiter data (cruise and nominal mission phase) to test whether the weakness of the relationship persists over a range of heliocentric distances. If the correlation is found to strengthen when closer to the Sun, then this would indicate an initial relationship which is being degraded, perhaps by wave-particle interactions, en route to the observer.

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“…In Figure (top and bottom) high‐speed streams identified by Ko et al . [] as originating in polar coronal holes are marked with a red central dot and high‐speed streams identified by Ko et al . [] as originating in equatorward extensions of coronal holes are marked with a green central dot.…”

Section: Intervals Of Unperturbed Coronal Hole Plasmamentioning

confidence: 99%

The plasma structure of coronal hole solar wind: Origins and evolution

Borovsky

2016

JGR Space Physics

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Whereas slow solar wind is known to be highly structured, the fast (coronal hole origin) wind is usually considered to be homogeneous. Using measurements from Helios 1 + 2, ACE, Wind, and Ulysses, structure in the coronal hole origin solar wind is examined from 0.3 AU to 2.3 AU. Care is taken to collect and analyze intervals of “unperturbed coronal hole plasma.” In these intervals, solar wind structure is seen in the proton number density, proton temperature, proton specific entropy, magnetic field strength, magnetic field to density ratio, electron heat flux, helium abundance, heavy‐ion charge‐state ratios, and Alfvenicity. Typical structure amplitudes are factors of 2, far from homogeneous. Variations are also seen in the solar wind radial velocity. Using estimates of the motion of the solar wind origin footpoint on the Sun for the various spacecraft, the satellite time series measurements are converted to distance along the photosphere. Typical variation scale lengths for the solar wind structure are several variations per supergranule. The structure amplitude and structure scale sizes do not evolve with distance from the Sun from 0.3 to 2.3 AU. An argument is quantified that these variations are the scale expected for solar wind production in open magnetic flux funnels in coronal holes. Additionally, a population of magnetic field foldings (switchbacks, reversals) in the coronal hole plasma is examined: this population evolves with distance from the Sun such that the magnetic field is mostly Parker spiral aligned at 0.3 AU and becomes more misaligned with distance outward.

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Temporal Evolution of Solar Wind Ion Composition and Their Source Coronal Holes During the Declining Phase of Cycle 23. I. Low-Latitude Extension of Polar Coronal Holes

Cited by 23 publications

References 51 publications

Charge States and FIP Bias of the Solar Wind from Coronal Holes, Active Regions, and Quiet Sun

Charge States and FIP Bias of the Solar Wind from Coronal Holes, Active Regions, and Quiet Sun

Tests for coronal electron temperature signatures in suprathermal electron populations at 1 AU

The plasma structure of coronal hole solar wind: Origins and evolution

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Temporal Evolution of Solar Wind Ion Composition and Their Source Coronal Holes During the Declining Phase of Cycle 23. I. Low-Latitude Extension of Polar Coronal Holes

Cited by 23 publications

References 51 publications

Charge States and FIP Bias of the Solar Wind from Coronal Holes, Active Regions, and Quiet Sun

Charge States and FIP Bias of the Solar Wind from Coronal Holes, Active Regions, and Quiet Sun

Tests for coronal electron temperature signatures in suprathermal electron populations at 1 AU

The plasma structure of coronal hole solar wind: Origins and evolution

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Product

Resources

About

Tests for coronal electron temperature signatures in suprathermal electron populations at 1 AU