Recently, the Hydrogen Epoch of Reionization Array (HERA) has produced the experiment’s first upper limits on the power spectrum of 21 cm fluctuations at
The Parker Solar Probe (PSP) entered a region of subAlfvénic solar wind during encounter 8, and we present the first detailed analysis of lowfrequency turbulence properties in this novel region. The magnetic field and flow velocity vectors were highly aligned during this interval. By constructing spectrograms of the normalized magnetic helicity, crosshelicity, and residual energy, we find that PSP observed primarily Alfvénic fluctuations, a consequence of the highly fieldaligned flow that renders quasi2D fluctuations unobservable to PSP. We extend Taylor’s hypothesis to sub and superAlfvénic flows. Spectra for the fluctuating forward and backward Elsässer variables (
 Award ID(s):
 1655280
 NSFPAR ID:
 10363015
 Publisher / Repository:
 DOI PREFIX: 10.3847
 Date Published:
 Journal Name:
 The Astrophysical Journal Letters
 Volume:
 926
 Issue:
 2
 ISSN:
 20418205
 Page Range / eLocation ID:
 Article No. L16
 Format(s):
 Medium: X
 Sponsoring Org:
 National Science Foundation
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