Solar wind velocity distribution on the heliospheric current sheet during Carrington rotations 1787–1795

1995 ◽  
Vol 13 (8) ◽  
pp. 807
Author(s):  
B. Bala ◽  
S. R. Prabhakaran Nayar
Keyword(s):  
Solar Wind ◽  
Velocity Distribution ◽  
Current Sheet ◽  
Wind Velocity ◽  
Solar Wind Velocity ◽  
Heliospheric Current Sheet

Solar wind velocity distribution on the heliospheric current sheet during Carrington rotations 1787-1795

1995 ◽  
Vol 13 (8) ◽  
pp. 807-814
Author(s):  
B. Bala ◽  
S. R. Prabhakaran Nayar
Keyword(s):  
Solar Wind ◽  
Velocity Distribution ◽  
Current Sheet ◽  
Wind Velocity ◽  
Solar Wind Velocity ◽  
Neutral Line ◽  
Coronal Magnetic Field ◽  
Heliospheric Current Sheet ◽  
Source Surface ◽  
Low Speed

Abstract. The solar wind velocity distribution in the heliosphere is best represented using a v-map, where velocity contours are plotted in heliographic latitude-longitude coordinates. It has already been established that low-speed regions of the solar wind on the source surface correspond to the maximum bright regions of the K-corona and the neutral line of the coronal magnetic field. In this analysis, v-maps on the source surface for Carrington rotations (CRs) 1787–1795, during 1987, have been prepared using the interplanetary scintillation measurements at Research Institute of Atmospherics (RIA), Nagoya Univ., Japan. These v-maps were then used to study the time evolution of the low-speed (\\leq450 km s–1) belt of the solar wind and to deduce the distribution of solar wind velocity on the heliospheric current sheet. The low-speed belt of the solar wind on the source surface was found to change from one CR to the next, implying a time evolution. Instead of a slow and systematic evolution, the pattern of distribution of solar wind changed dramatically at one particular solar rotation (CR 1792) and the distributions for the succeeding rotations were similar to this pattern. The low-speed region, in most cases, was found to be close to the solar equator and almost parallel to it. However, during some solar rotations, they were found to be organised in certain longitudes, leaving regions with longitudinal width greater than 30° free of low-speed solar wind, i.e. these regions were occupied by solar wind with velocities greater than 450 km s–1. It is also noted from this study that the low-speed belt, in general, followed the neutral line of the coronal magnetic field, except in certain cases. The solar wind velocity on the heliospheric current sheet (HCS) varied in the range 300–585 km s–1 during the period of study, and the pattern of velocity distribution varied from rotation to rotation.

Ripples in the Heliospheric Current Sheet: Dependence on Latitude and Transient Outflows

2021 ◽  
Author(s):  
Ronan Laker ◽  
Timothy Horbury ◽  
Lorenzo Matteini ◽  
Thomas Woolley ◽  
Lloyd Woodham ◽  
...  
Keyword(s):  
Solar Wind ◽  
Current Sheet ◽  
Wind Velocity ◽  
Solar Wind Velocity ◽  
Three Dimensional ◽  
Heliospheric Current Sheet ◽  
Magnetic Polarity ◽  
Magnetic Clouds ◽  
Magnetic Structures ◽  
Interaction Regions

<p>The recent launches of Parker Solar Probe (PSP), Solar Orbiter (SO) and BepiColombo, along with several legacy spacecraft, have provided the opportunity to study the solar wind at multiple latitudes and distances from the Sun simultaneously. We take advantage of this unique spacecraft constellation, along with low solar activity between May and July 2020, to investigate how latitude affects the solar wind and Heliospheric Current Sheet (HCS) structure. We use ballistic mapping to compare polarity and solar wind velocity between several spacecraft, showing that fine scale ripples in the HCS can be resolved down to several degrees in longitude. We show that considering solar wind velocity is also useful when investigating the HCS structure, as it can reveal times when the spacecraft is within slow, dense streamer belt wind without changing magnetic polarity. We measured the local orientation of planar magnetic structures associated with HCS crossings, finding that these were broadly consistent with the shape of the HCS but at much steeper angles due to compression from stream interaction regions. We identified several transient magnetic clouds associated with HCS crossings, and have shown that these can disrupt the local HCS orientation up to four days after their passage, but did not significantly affect the position of the HCS. This work highlights that the heliosphere should always be treated as three-dimensional, especially at solar minimum, where a few degrees in latitude can create a considerable difference in solar wind conditions.</p>

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