Articles | Volume 35, issue 1 
            
                
                    
            
            
            https://doi.org/10.5194/angeo-35-71-2017
                    © Author(s) 2017. This work is distributed under 
the Creative Commons Attribution 3.0 License.
                the Creative Commons Attribution 3.0 License.
https://doi.org/10.5194/angeo-35-71-2017
                    © Author(s) 2017. This work is distributed under 
the Creative Commons Attribution 3.0 License.
                the Creative Commons Attribution 3.0 License.
Absence of the strahl during times of slow wind
Chris Gurgiolo
CORRESPONDING AUTHOR
                                            
                                    
                                            Bitterroot Basic Research, Hamilton, MT, USA
                                        
                                    Melvyn L. Goldstein
                                            Heliospheric Physics Laboratory, Code 672, NASA Goddard Space Flight
Center, Greenbelt, MD, USA
                                        
                                    Related authors
Chris Gurgiolo and Melvyn L. Goldstein
                                    Ann. Geophys., 34, 1175–1189, https://doi.org/10.5194/angeo-34-1175-2016, https://doi.org/10.5194/angeo-34-1175-2016, 2016
                                    Short summary
                                    Short summary
                                            
                                                Using Cluster data we have noted observations of diffusion-like signatures in the energy range where the the solar wind halo and strahl populations overlap. This includes the development of a proto-halo. At present the source of this diffusion is not known or understood. The prime analysis was carried out through the use of phi–theta plots at individual energy steps.  The motivation was to understand if repartitioning in energy was occurring at these locations.
                                            
                                            
                                        C. Gurgiolo, M. L. Goldstein, W. H. Matthaeus, A. Viñas, and A. N. Fazakerley
                                    Ann. Geophys., 31, 2063–2075, https://doi.org/10.5194/angeo-31-2063-2013, https://doi.org/10.5194/angeo-31-2063-2013, 2013
                            Christopher A. Gurgiolo, Melvyn L. Goldstein, and Adolfo Viñas
                                    Ann. Geophys., 37, 243–261, https://doi.org/10.5194/angeo-37-243-2019, https://doi.org/10.5194/angeo-37-243-2019, 2019
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                                                The reflection of solar wind electrons at the bow shock helps define the physical properties of the foreshock, the region where the interplanetary magnetic field directly connects to the bow shock. We report that the strahl, the field-aligned component of the electron solar wind distribution, appears to be nearly fully reflected at the bow shock and that the reflection occurs in the foot of the shock, implying that mirroring is not the primary cause of the electron reflection.
                                            
                                            
                                        Chris Gurgiolo and Melvyn L. Goldstein
                                    Ann. Geophys., 34, 1175–1189, https://doi.org/10.5194/angeo-34-1175-2016, https://doi.org/10.5194/angeo-34-1175-2016, 2016
                                    Short summary
                                    Short summary
                                            
                                                Using Cluster data we have noted observations of diffusion-like signatures in the energy range where the the solar wind halo and strahl populations overlap. This includes the development of a proto-halo. At present the source of this diffusion is not known or understood. The prime analysis was carried out through the use of phi–theta plots at individual energy steps.  The motivation was to understand if repartitioning in energy was occurring at these locations.
                                            
                                            
                                        C. Gurgiolo, M. L. Goldstein, W. H. Matthaeus, A. Viñas, and A. N. Fazakerley
                                    Ann. Geophys., 31, 2063–2075, https://doi.org/10.5194/angeo-31-2063-2013, https://doi.org/10.5194/angeo-31-2063-2013, 2013
                            Short summary
            Observations during periods when the solar wind has a speed < 425 km s−1 show that it is not uncommon to find no strahl present in the data. The research was done in response to observations and was performed through a detailed study of the electron velocity distribution functions. The conclusion arrived at is that the absence of the strahl appears to occur within individual flux tubes, which may indicate that the source lies  in the solar corona where the strahl is formed.
            Observations during periods when the solar wind has a speed < 425 km s−1 show that it is not uncommon to... 425 km s
            
         
 
                        
                                         
             
             
             
            