Relating Streamer Flows to Density and Magnetic Structures at the Parker Solar Probe

Rouillard, A. P.; Kouloumvakos, A.; Vourlidas, A.; Kasper, J. C.; Bale, S. D.; Raouafi, N. E.; Lavraud, B.; Howard, R. A.; Stenborg, G.; Stevens, Michael L.; Poirier, Nicolas; Davies, J. A.; Hess, Phillip; Higginson, A. K.; Lavarra, M.; Viall, N. M.; Korreck, K. E.; Pinto, Rui; Griton, Léa; Réville, Victor; Louarn, P.; Wu, Yuling; Dalmasse, K.; Génot, Vincent; Case, A. W.; Whittlesey, P. L.; Larson, D. E.; Halekas, J. S.; Livi, R.; Goetz, K.; Harvey, P.; MacDowall, R. J.; Malaspina, D.; Pulupa, M.; Bonnell, J. W.; Wit, T. Dudok de; Penou, E.

doi:10.3847/1538-4365/ab579a

Cited by 67 publications

(45 citation statements)

References 63 publications

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“…Rouillard, Kouloumvakos, et al. (2020) confirmed the relationship between mesoscale density structures observed in images and in situ by tracking larger streamer blobs with embedded approximately hourlong structures from STEREO SECCHI to their impact with Parker Solar Probe. In short, it is now clear that the solar wind is often formed of quasi‐periodic mesoscale plasma density structures released as a part of solar wind formation.…”

Section: Introductionmentioning

confidence: 67%

“…More recently, Rouillard, Kouloumvakos, et al. (2020) tracked density structures through the STEREO COR2 and HI1 FOVs to their impact at Parker Solar Probe, where they observed a one‐to‐one correlation between the ∼3–4 hr density structures observed remotely and the in situ Parker measurements. They showed that Parker measured additional sequences of small density peaks separated in time by approximately 90–120 min, suggestive of the types of periodic density enhancements at 90 min time scales that have been observed in situ at L1 (Kepko & Spence, 2003; Viall et al., 2008), near Mercury's orbit with Helios (Matteo et al., 2019), and remotely with STEREO (Viall & Vourlidas, 2015).…”

Section: Discussionmentioning

confidence: 99%

“…Solar wind structures throughout this range of “mesoscale” sizes have been identified in Solar Terrestrial Relations Observatory (STEREO) white light remote sensing data down to the resolution of the imager (DeForest et al., 2018; Viall & Vourlidas, 2015). They have also been observed in situ, in the form of magnetic field flux rope structures as small as 50 Mm (Murphy et al., 2020), in plasma density at scales between 50 and 2,000 Mm (Stansby & Horbury, 2018), and in combinations of magnetic and plasma signatures (Borovsky, 2008; Matteo et al., 2019; Rouillard, Lavraud, et al., 2010; Rouillard, Kouloumvakos, et al., 2020; Sanchez‐Diaz et al., 2019).…”

Section: Introductionmentioning

confidence: 97%

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Inherent Length Scales of Periodic Mesoscale Density Structures in the Solar Wind Over Two Solar Cycles

2020

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It is now well established through multiple event and statistical studies that the solar wind at 1 AU contains contains periodic, mesoscale (L ∼ 100–1,000 Mm) structures in the proton density. Composition variations observed within these structures and remote sensing observations of similar structures in the young solar wind indicate that at least some of these periodic structures originate in the solar atmosphere as a part of solar wind formation. Viall et al. (2008, https://doi.org/10.1029/2007JA012881) analyzed 11 years of data from the Wind spacecraft near L1 and demonstrated a recurrence to the observed length scales of periodic structures in the solar wind proton density. In the time since that study, Wind has collected 14 additional years of solar wind data, new moment analysis of the Wind SWE data is available, and new methods for spectral background approximation have been developed. In this study, we analyze 25 years of Wind data collected near L1 and produce occurrence distributions of statistically significant periodic length scales in proton density. The results significantly expand upon the Viall et al. (2008, https://doi.org/10.1029/2007JA012881) study and further show a possible relation of the length scales to solar “termination” events.

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Section: Introductionmentioning

confidence: 67%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

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Inherent Length Scales of Periodic Mesoscale Density Structures in the Solar Wind Over Two Solar Cycles

2020

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“…Disconnections will certainly result in a decreased strahl intensity. The second source is interchange reconnection between open field lines and closed loops of streamers (Wang et al, 2000;Crooker et al, 2004;Rouillard et al, 2020). Individual interchange reconnection events, which change the magnetic connection into loops of different heights and electron temperatures, will almost certainly result in a change in the strahl intensity.…”

Section: The Electron Strahl and The Types Of Solar Wind Plasmamentioning

confidence: 99%

Exploring the Properties of the Electron Strahl at 1 AU as an Indicator of the Quality of the Magnetic Connection Between the Earth and the Sun

Borovsky

2021

Front. Astron. Space Sci.

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In this report some properties of the electron strahl at 1 AU are examined to assess the strahl at 272 eV as an indicator of the quality of the magnetic connection of the near-Earth solar wind to the Sun. The absence of a strahl has been taken to represent either a lack of magnetic connection to the corona or the strahl not surviving to 1 AU owing to scattering. Solar-energetic-electron (SEE) events can be used as indicators of good magnetic connection: examination of 216 impulsive SEE events finds that they are all characterized by strong strahls. The strahl intensity at 1 AU is statistically examined for various types of solar-wind plasma: it is found that the strahl is characteristically weak in sector-reversal-region plasma. In sector-reversal-region plasma and other slow wind, temporal changes in the strahl intensity at 1 AU are examined with 64 s resolution measurements and the statistical relationships of strahl changes to simultaneous plasma-property changes are established. The strahl-intensity changes are co-located with current sheets (directional discontinuities) with strong changes in the magnetic-field direction. The strahl-intensity changes at 1 AU are positively correlated with changes in the proton specific entropy, the proton temperature, and the magnetic-field strength; the strahl-intensity changes are anti-correlated with changes in the proton number density, the angle of the magnetic field with respect to the Parker-spiral direction, and the alpha-to-proton number-density ratio. Reductions in the strahl intensity are not consistent with expectations for a simple model of whistler-turbulence scattering. Reductions in the strahl intensity are mildly consistent with expectations for Coulomb scattering, however the strongest-observed plasma-change correlations are unrelated to Coulomb scattering and whistler scattering. The implications of the strahl-intensity-change analysis are that the change in the magnetic-field direction at a strahl change represents a change in the magnetic connection to the corona, resulting in a different strahl intensity and different plasma properties. An outstanding question is: Does an absence of an electron strahl represent a magnetic disconnection from the Sun or a poor strahl source in some region of the corona?

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“…We observe some brightening located at the core of the northern streamer and some bright spike-like features that appear periodically near the streamer edges. These are transient perturbations of the streamer associated with the passage of two consecutive CMEs (Hess et al 2020;Rouillard et al 2020) indicated by two white arrows on the WISPR map. The southern streamer is more diffuse and exhibits much less activity with the exception of the passage of the first CME which originated in the northern streamer and was deflected southward during its transit through the corona to WISPR.…”

Section: Wispr Carrington Mapsmentioning

confidence: 99%

Detailed Imaging of Coronal Rays with the Parker Solar Probe

Poirier

Kouloumvakos

Rouillard

et al. 2020

ApJS

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The Wide-field Imager for Solar PRobe (WISPR) obtained the first high-resolution images of coronal rays at heights below 15 R when Parker Solar Probe (PSP ) was located inside 0.25 au during the first encounter. We exploit these remarkable images to reveal the structure of coronal rays at scales that are not easily discernible in images taken from near 1 au. To analyze and interpret WISPR observations, which evolve rapidly both radially and longitudinally, we construct a latitude versus time map using the full WISPR dataset from the first encounter. From the exploitation of this map and also from sequential WISPR images, we show the presence of multiple substructures inside streamers and pseudostreamers. WISPR unveils the fine-scale structure of the densest part of streamer rays that we identify as the solar origin of the heliospheric plasma sheet typically measured in situ in the solar wind. We exploit 3D magnetohydrodynamic models, and we construct synthetic white-light images to study the origin of the coronal structures observed by WISPR. Overall, including the effect of the spacecraft relative motion toward the individual coronal structures, we can interpret several observed features by WISPR. Moreover, we relate some coronal rays to folds in the heliospheric current sheet that are unresolved from 1 au. Other rays appear to form as a result of the inherently inhomogeneous distribution of open magnetic flux tubes.

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Relating Streamer Flows to Density and Magnetic Structures at the Parker Solar Probe

Cited by 67 publications

References 63 publications

Inherent Length Scales of Periodic Mesoscale Density Structures in the Solar Wind Over Two Solar Cycles

Inherent Length Scales of Periodic Mesoscale Density Structures in the Solar Wind Over Two Solar Cycles

Exploring the Properties of the Electron Strahl at 1 AU as an Indicator of the Quality of the Magnetic Connection Between the Earth and the Sun

Detailed Imaging of Coronal Rays with the Parker Solar Probe

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