Institut national de recherche scientifique français Univerité Pierre et Marie Curie Université Paris Diderot - Paris 7

The slow solar winds measured by Parker Solar Probe during the first and second perihelia

vendredi 28 février 2020, par Léa Griton (IRAP)

Mardi 3 mars 2020 à 11h00 , Lieu : Salle de rĂ©union du bâtiment 16

The recent analysis of Parker Solar Probe’s (PSP’s) second encounter compared with data taken by the Solar and Heliospheric Observatory (SOHO) and Solar TErrestrial RElations Observatory (STEREO) A (STA) revealed for the first time a close link between the high-density plasma measured by PSP and streamer flows imaged by instruments at 1 AU from the Sun (Rouillard et al, 2020, ApJS). Observations when STA was in orbital quadrature with PSP were used to track the release and propagation of dense material from the corona to PSP. The analysis of time-elongation maps, built from STA images, show that PSP was impacted continually by the southern edge of streamer transients inducing clear density increases measured in situ by the plasma instrument. Considering PSP’s first and second encounters, we then identified different time intervals when PSP is above a streamer and then above a coronal hole. We find evidence that the occurence of magnetic field reversals, the main plasma properties (plasma beta, compressibility, variability on MHD scales) changes from one region to another. These magnetic reversals are associated with strong density variations when associated with streamer flows, but with weak density variations outside streamer flows. We present a detailed analysis of the properties of the solar wind, and more specifically of switchbacks in these different slow flows, above streamers and above coronal holes. We compare the magnetic and speed components as well as the correlation between speed, density and temperature.