Abstract In January 2021, Metis/SolO and PSP formed a quadrature from which the slow solar wind was able to be measured from the extended solar corona (3.5 – 6.3 R ⊙ ) to the very inner heliosphere (23.2 R ⊙ ). Metis/SolO remotely measured the coronal solar wind, finding a speed of 96 – 201 kms −1 , and PSP measured the solar wind in situ, finding a speed of 219.34 kms −1 . Similarly, the normalized cross-helicity and the normalized residual energy measured by PSP are 0.96 and -0.07. In this manuscript, we study the evolution of the proton entropy and the turbulence cascade rate of the outward Elsässer energy during this quadrature. We also study the relationship between solar wind speed, density and temperature, and their relationship with the turbulence energy, the turbulence cascade rate, and the solar wind proton entropy. We compare the theoretical results with the observed results measured by Metis/SolO and PSP.
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Modeling of Joint Parker Solar Probe–Metis/Solar Orbiter Observations
Abstract We present the first theoretical modeling of joint Parker Solar Probe (PSP)–Metis/Solar Orbiter (SolO) quadrature observations. The combined observations describe the evolution of a slow solar wind plasma parcel from the extended solar corona (3.5–6.3 R ⊙ ) to the very inner heliosphere (23.2 R ⊙ ). The Metis/SolO instrument remotely measures the solar wind speed finding a range from 96 to 201 km s −1 , and PSP measures the solar wind plasma in situ, observing a radial speed of 219.34 km s −1 . We find theoretically and observationally that the solar wind speed accelerates rapidly within 3.3–4 R ⊙ and then increases more gradually with distance. Similarly, we find that the theoretical solar wind density is consistent with the remotely and in-situ observed solar wind density. The normalized cross helicity and normalized residual energy observed by PSP are 0.96 and −0.07, respectively, indicating that the slow solar wind is very Alfvénic. The theoretical NI/slab results are very similar to PSP measurements, which is a consequence of the highly magnetic field-aligned radial flow ensuring that PSP can measure slab fluctuations and not 2D ones. Finally, we calculate the theoretical 2D and slab turbulence pressure, finding that the theoretical slab pressure is very similar to that observed by PSP.
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- Award ID(s):
- 1655280
- NSF-PAR ID:
- 10391860
- Date Published:
- Journal Name:
- The Astrophysical Journal Letters
- Volume:
- 937
- Issue:
- 2
- ISSN:
- 2041-8205
- Page Range / eLocation ID:
- L29
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract We present a theoretical and observational study of 2D and slab turbulence cascade (or heating) rates of transverse total turbulence energies, transverse cross helicity, transverse outward and inward Elsässer energy, transverse fluctuating magnetic energy density, and transverse fluctuating kinetic energy from the perihelion of the first Parker Solar Probe (PSP) orbit at ∼36.6 R ⊙ to Solar Orbiter (SolO) at ∼177 R ⊙ . We use the Adhikari et al. (2021a) approach to calculate the observed transverse turbulence heating rate, and the nearly incompressible magnetohydrodynamic (NI MHD) turbulence transport theory to calculate the theoretical turbulence cascade rate. We find from the 1 day long PSP measurements at 66.5 R ⊙ , and the SolO measurements at 176.3 R ⊙ that various transverse turbulent cascade rates increase with increasing angle, from 10° to 98°, between the mean solar wind speed and mean magnetic field ( θ UB ), indicating that the 2D heating rate is largest in the inner heliosphere. Similarly, we find from the theoretical and observed results that the 2D heating rate is larger than the slab heating rate as a function of heliocentric distance. We present a comparison between the theoretical and observed 2D and slab turbulence cascade rates as a function of heliocentric distance.more » « less
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.3847/2041-8213/ac91c6
