Prediction and Verification of Parker Solar Probe Solar Wind Sources at 13.3 R_⊙

Abstract

Drawing connections between heliospheric spacecraft and solar wind sources is a vital step in understanding the evolution of the solar corona into the solar wind and contextualizing in situ timeseries. Furthermore, making advanced predictions of this linkage for ongoing heliospheric missions, such as Parker Solar Probe (Parker), is necessary for achieving useful coordinated remote observations and maximizing scientific return. The general procedure for estimating such connectivity is straightforward (i.e., magnetic field line tracing in a coronal model) but validating the resulting estimates is difficult due to the lack of an independent ground truth and limited model constraints. In its most recent orbits, Parker has reached perihelia of 13.3R⊙ and moreover travels extremely fast prograde relative to the solar surface, covering over 120° longitude in 3 days. Here we present footpoint predictions and subsequent validation efforts for Parker Encounter 10, the first of the 13.3R⊙ orbits, which occurred in November 2021. We show that the longitudinal dependence of in situ plasma data from these novel orbits provides a powerful method of footpoint validation. With reference to other encounters, we also illustrate that the conditions under which source mapping is most accurate for near‐ecliptic spacecraft (such as Parker) occur when solar activity is low, but also require that the heliospheric current sheet is strongly warped by mid‐latitude or equatorial coronal holes. Lastly, we comment on the large‐scale coronal structure implied by the Encounter 10 mapping, highlighting an empirical equatorial cut of the Alfvèn surface consisting of localized protrusions above unipolar magnetic separatrices.

Quantifying the Energy Budget in the Solar Wind from 13.3 to 100 Solar Radii

“…Unfortunately, with a single spacecraft, we can never accomplish this, though we note that others have started to investigate PSP-Solar Orbiter conjunctions (Telloni et al 2021;Réville et al 2022;Telloni et al 2022b), which may help achieve this goal. Nonetheless, thanks to the orbital dynamics that the PSP spacecraft experiences near perihelion, we do often have the opportunity to sample the same streams at multiple radii (Shi et al 2021;Badman et al 2023). These repeated crossings of a single flux tube have been dubbed fast radial scans (Fox et al 2016).…”

Whole Heliosphere and Planetary Interactions (WHPI): The Big Picture on Solar Cycle Minima

“…These included the solar eclipse in July 2019—which was studied both for its solar structure (Lloveras et al., 2022, a paper in this collection) and for the Earth's thermospheric response to it as measured by the GOLD satellite (Aryal et al., 2020). They also included the Parker Solar Probe perihelion passage in January 2020—which served as a template for community coordination and predictive targeting (Badman et al., 2023, a paper in this collection). Beyond that, we trusted to solar serendipity to provide interesting time periods for study, and we were not disappointed!…”

The Evolution of the 1/f Range within a Single Fast-solar-wind Stream between 17.4 and 45.7 Solar Radii

“…In this paper, we have examined magnetic field data from PSP's Encounter 10, specifically from 2021 November 17 to 20. During this interval, PSP was moving approximately radially within fast solar wind, as illustrated in Figure 1, and was magnetically connected to a single midlatitude coronal hole (Badman et al 2023). The magnetic power spectra presented here all show an approximate double power-law form over the frequency range (10 −4 s −1 , 10 0 s −1 ), with a break frequency f b that gradually decreases as r increases.…”

“…In this study, we analyze magnetic field and velocity data from PSP Encounter 10 from 2021 November 17 to 20, covering a heliocentric radial distance range 0.08-0.22 au (17.4 to 45.7 R s ). Over the entirety of PSP's Encounter 10, PSP connected to a series of three isolated midlatitude negativepolarity coronal holes (Badman et al 2023). PSP traversed all three in rapid succession as it moved prograde over the solar surface near perihelion.…”

“…From November 17 to 19, the footpoints moved very slighly in retrograde, away from the center (peak) of the fast wind stream and toward the east limb. Over the remainder of November 19, PSP went through corotation and then began to migrate slowly prograde before passing over the fastest part of the stream around midday on November 20 (Badman et al 2023). The data interval that we analyze basically provides a radial scan of the same fast-solar-wind stream.…”