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

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http://hdl.handle.net/10138/230196

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Sanchez-Diaz , E , Rouillard , A P , Davies , J A , Lavraud , B , Pinto , R F & Kilpua , E 2017 , ' The Temporal and Spatial Scales of Density Structures Released in the Slow Solar Wind During Solar Activity Maximum ' , Astrophysical Journal , vol. 851 , no. 1 , 32 . https://doi.org/10.3847/1538-4357/aa98e2

Title: The Temporal and Spatial Scales of Density Structures Released in the Slow Solar Wind During Solar Activity Maximum
Author: Sanchez-Diaz, E.; Rouillard, A. P.; Davies, J. A.; Lavraud, B.; Pinto, R. F.; Kilpua, E.
Contributor: University of Helsinki, Department of Physics
Date: 2017-12-10
Language: eng
Number of pages: 17
Belongs to series: Astrophysical Journal
ISSN: 0004-637X
URI: http://hdl.handle.net/10138/230196
Abstract: 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 well-defined 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.
Subject: methods: observational
solar wind
Sun: corona
Sun: general
Sun: heliosphere
Techniques: image processing
HELIOSPHERIC PLASMA SHEETS
DYNAMICS-OBSERVATORY SDO
HEAT-FLUX DROPOUTS
1 AU
MAGNETOHYDRODYNAMIC MODELS
MAGNETIC-FIELDS
CORONAL INFLOWS
STREAMER BLOBS
RECONNECTION
SUN
115 Astronomy, Space science
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