Connecting the Low to High Corona: Tracking Outward Propagating Small-Scale Structures Using EUV and Coronagraph Observations

Abstract:

Previous studies have identified density structures in the slow solar wind that can be traced down through the field of view (FOV) of STEREO A/COR2. Advanced image processing techniques can reveal small, faint, formerly hidden structures in extreme ultraviolet (EUV) and white light (WL) data providing continuous tracking of brightness enhancements from the coronal base to the radial extended corona. Our most recent work, carried out using STEREO/COR1 observations, proved crucial in linking the low to the high corona. Our method for processing COR1, which facilitates the tracking of small-scale outward propagating structures, was applied to several time periods of observations during Solar cycle 24 for the study of the sources of the slow solar wind. We identified the outflows in ancillary data from multiple WL coronagraphs as well as EUV instruments, including STEREO/EUVI and GOES-R/SUVI when available. The outflows were tracked across the different FOVs from carefully chosen datasets based on spacecraft position. The larger FOV of SUVI enabled an uninterrupted view of outflows from the Sun through images from corresponding coronagraph observations. In doing so, we were able to link structures near the Sun where the magnetic field structure is highly non-radial to their counterparts higher up where the magnetic field follows a radial path. Our work opens the door for studies of the origin of small-scale structures in the heliosphere and their implications for the sources of the slow solar wind.