Analysis of WISPR Images of the Near-Sun Heliospheric Current Sheet Region from Parker Solar Probe Encounters 4 and 5 and Comparison with the in-situ Observations

We present an analysis of Wide-field Imager for Solar PRobe (WISPR) images of the near-Sun Heliospheric Current Sheet (HCS) region from Parker Solar Probe (PSP) in January and June 2020. Previous analysis of the solar wind data from PSP’s in-situ instruments for these periods had shown multiple signatures of magnetic reconnection during HCS encounters (Phan et al., 2021). The signatures, including field-line disconnections, density enhancements, and reconnection flows, indicated that reconnection was nearly always active in the HCS near the Sun. Here we present an analysis of WISPR white-light observations of the HCS region during the same time periods using an image processing technique that enhances changes in the images from frame to frame. This processing reveals the presence of a nearly continual stream of transient density enhancements (“blobs”) within the helmet streamer flow not evident in the standard calibrated-brightness images. The blobs observed frequently in helmet streamer flows by white light imagers, are broadly interpreted as resulting from reconnection in the vicinity of the HCS. Thus, the WISPR observations are consistent with the in-situ data finding that reconnection is almost always active in the HCS near the Sun. We use the Tracking and Fitting technique (Liewer2020, Liewer2022} to determine the trajectory and size of a few more distinct blobs. We confirm that the blobs lie near the HCS and find that the size of the imaged blobs is similar to the size estimates for possible blobs seen in situ in the HCS at similar distance from the Sun (Phan et al., 2021).