Small solar wind transients at 1 AU: STEREO observations (2007–2014) and comparison with near‐Earth wind results (1995–2014)

Yu, Wenyuan; Farrugia, C. J.; Galvin, A. B.; Lugaz, Noé; Luhmann, J. G.; Simunac, K. D. C.; Kilpua, Emilia

doi:10.1002/2016ja022642

Cited by 41 publications

(58 citation statements)

References 58 publications

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“…Rouillard et al (2010aRouillard et al ( , 2010b demonstrated the tracking of blobs all the way to their in situ detection at 1 au in combined STEREO observations; the authors showed that these blobs were associated, in in situ measurements, to the passage of kinks and loops that were likely part of magnetic flux ropes. Similar transient structures had previously been detected in in situ measurements alone (e.g., Crooker et al 1996Crooker et al , 2004Kilpua et al 2009;Yu et al 2016). More recently, Plotnikov et al (2016) mapped blob emission along the ecliptic plane over nearly a complete solar cycle.…”

Section: Introductionsupporting

confidence: 84%

The Temporal and Spatial Scales of Density Structures Released in the Slow Solar Wind During Solar Activity Maximum

Sanchez-Diaz

Rouillard

Davies

et al. 2017

ApJ

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In a recent study, we took advantage of a highly tilted coronal neutral sheet to show that density structures, extending radially over several solar radii (R s ), are released in the forming slow solar wind approximately 4-5 R s above the solar surface. We related the signatures of this formation process to intermittent magnetic reconnection occurring continuously above helmet streamers. We now exploit the heliospheric imagery from the Solar Terrestrial Relation Observatory (STEREO) to map the spatial and temporal distribution of the ejected structures. We demonstrate that streamers experience quasi-periodic bursts of activity with the simultaneous outpouring of small transients over a large range of latitudes in the corona. This cyclic activity leads to the emergence of welldefined and broad structures. Derivation of the trajectories and kinematic properties of the individual small transients that make up these large-scale structures confirms their association with the forming slow solar wind (SSW). We find that these transients are released, on average, every 19.5 hr, simultaneously at all latitudes with a typical radial size of 12 R s . Their spatial distribution, release rate, and three-dimensional extent are used to estimate the contribution of this cyclic activity to the mass flux carried outward by the SSW. Our results suggest that, in interplanetary space, the global structure of the heliospheric current sheet is dominated by a succession of blobs and associated flux ropes. We demonstrate this with an example event using STEREO-A in situ measurements.

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Section: Introductionsupporting

confidence: 84%

The Temporal and Spatial Scales of Density Structures Released in the Slow Solar Wind During Solar Activity Maximum

Sanchez-Diaz

Rouillard

Davies

et al. 2017

ApJ

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“…The imaging observations may provide direct evidences, but this method is generally based on appropriate conditions (such as SFRs should be entrained by corotating interaction regions; e.g., Rouillard et al, , ), which may reduce the accuracy. Several studies investigated the source regions of SFRs using in situ characteristics (e.g., Cartwright & Moldwin, ; Feng & Wang, ; Feng et al, ; Janvier et al, ; Tian et al, ; Yu et al, , ); however, they generally relied on statistical results. Consequently, it is difficult to identify the source region of a specific SFR without sufficiently utilizing the compositional signatures of individual SFRs.…”

Section: Observation and Discussionmentioning

confidence: 99%

“…MCs are of great interest due to their associations with strong solar eruptions and potentially immense geoeffectiveness (e.g., H. Hu et al, ; Wang, Zhang, et al, ). SFRs contribute mainly to slow solar wind, and their source regions and formation mechanisms are still under discussion (e.g., Feng et al, , ; Janvier et al, , ; Kilpua et al, ; Tian et al, ; Yu et al, , ; Zheng & Hu, ).…”

Section: Introductionmentioning

confidence: 99%

“…Different from MCs that originate from the solar corona, SFRs are believed to have two source regions: the solar corona and the interplanetary medium (e.g., Cartwright & Moldwin, ; Feng et al, ; Janvier et al, ; Moldwin et al, ; Rouillard et al, ; Tian et al, ; Yu et al, , ). SFRs originating in the solar corona can be classified into two categories.…”

Section: Introductionmentioning

confidence: 99%

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The Distributions of Iron Average Charge States in Small Flux Ropes in Interplanetary Space: Clues to Their Twisted Structures

et al. 2018

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Small flux ropes (SFRs) have been studied for decades, but their source regions and formation mechanisms are still under debate. In this study, we focus on the formation mechanism of the twisted structures of SFRs. Current research on magnetic clouds suggests five‐type distributions of the time structure of iron average charge states (Q), which imply different formation mechanisms of twisted structures. We use a similar method to identify the Q types of 25 SFRs. However, only four of these five types of distributions are found among these SFRs. Because different origins of SFRs are characteristically affecting the formation of Q types, the possible source regions of these SFRs are distinguished. With additional compositional parameters, SFRs are reconfirmed to originate from two types of source regions: the solar corona and the interplanetary medium. Based on these results, our analysis indicates that the twisted structures of SFRs originating from the solar corona may be formed predominately during eruptions. SFRs originating from interplanetary space are related to complex magnetic reconnection processes, which may result in intricate Q distributions due to the reconstruction of magnetic field topology.

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“…The large‐scale MCs, which have been thoroughly studied, are associated with strong solar eruptions and drive major space weather events [e.g., Lawrance et al , ; Liu et al , ]. The origins of SFRs and their contributions to the slow solar wind have attracted much attention in recent years [ Moldwin et al , ; Kilpua et al , ; Rouillard et al , ; Feng et al , ; Yu et al , , ].…”

Section: Introductionmentioning

confidence: 99%

A multispacecraft study of a small flux rope entrained by rolling back magnetic field lines

et al. 2017

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We present a small flux rope (SFR) with smooth magnetic field rotations entrained by rolling back magnetic field lines around 1 AU. Such SFRs have only been seldom reported in the literature. This SFR was adjacent to a heliospheric plasma sheet (HPS), which is defined as a high plasma beta region in the vicinity of a heliospheric current sheet. Even though the SFR and HPS have different plasma beta, they possess similar plasma signatures (such as temperature, density, and bulk speed), density ratio of alpha particle‐to‐proton (Nα/Np), and heavy ion ionization states, which imply that they may have a similar origin in the corona. The composition and the configuration of the rolling back magnetic field lines suggested that the SFR originated from the streamer belt through interchange reconnection. The origin processes of the SFR are presented here. Combining the observations of STEREO and ACE, the SFR was shown to have an axis tilted to the ecliptic plane and the radius may vary with different spatial positions. In this study, we suggest that interchange reconnection can play an important role for the origin of, at least, some SFRs and slow solar wind.

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Small solar wind transients at 1 AU: STEREO observations (2007–2014) and comparison with near‐Earth wind results (1995–2014)

Cited by 41 publications

References 58 publications

The Temporal and Spatial Scales of Density Structures Released in the Slow Solar Wind During Solar Activity Maximum

The Temporal and Spatial Scales of Density Structures Released in the Slow Solar Wind During Solar Activity Maximum

The Distributions of Iron Average Charge States in Small Flux Ropes in Interplanetary Space: Clues to Their Twisted Structures

A multispacecraft study of a small flux rope entrained by rolling back magnetic field lines

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