BibTex format
@article{Ogasawara:2026:1538-4357/ae9153,
author = {Ogasawara, K and Dewey, RM and Allegrini, F and Alterman, BL and Galvin, A and Horbury, TS and Kistler, L and Lepri, ST and Livi, SA and Louarn, P and Owen, CJ and Raines, JM and Spitzer, SA},
doi = {1538-4357/ae9153},
journal = {Astrophysical Journal},
title = {Resolving Compositional Features of Solar Wind Source Regions near the Heliospheric Current Sheet at 0.3 au},
url = {http://dx.doi.org/10.3847/1538-4357/ae9153},
volume = {1008},
year = {2026}
}
RIS format (EndNote, RefMan)
TY - JOUR
AB - The Heavy Ion Sensor in Solar Wind Analyser suite on Solar Orbiter has provided unprecedented high-resolution elemental and ionic signatures around the heliospheric current sheet (HCS) from a vantage point near the Sun. Its high cadence time-series observations are used to determine the magnetic connectivity and map these complex transitions, revealing embedded processes of the observed signatures around the HCS crossing at ∼0.3 au. Electron strahl dropouts observed before the HCS crossing are accompanied by distinct local drops in the oxygen–proton temperature ratio (T<inf>O</inf>/T<inf>p</inf>), while carbon and oxygen charge-state ratios remain nearly invariant, with at most slight reductions depending on the interval. In contrast, near the true sector boundary (TSB) the heavy-ion composition profiles remain nearly constant, despite marked changes in magnetic and strahl topology. These measurements show that small-scale HCS-related structures at 0.3 au can be systematically matched with their heavy-ion thermal and compositional signatures. A gradual decrease of the Fe/O ratio toward the TSB is observed, reaching a minimum of (4.54 ± 0.54) × 10<sup>−2</sup> at the sector boundary and recovering within a few hours, establishing a clear association between Fe/O depletion and the HCS. After the HCS crossing, T<inf>O</inf>/T<inf>p</inf> frequently exceeds the super-mass-proportional threshold and is positively correlated with O<sup>7+</sup>/O<sup>6+</sup>, while C<sup>6+</sup>/C<sup>5+</sup> shows a negative correlation, indicating distinct properties of fully striped carbon within the same sector. As these signatures undergo minimal distortion during radial propagation and evolution, the observations presented in this study offer critical insights into the plasma provenance and the underlying physical proces
AU - Ogasawara,K
AU - Dewey,RM
AU - Allegrini,F
AU - Alterman,BL
AU - Galvin,A
AU - Horbury,TS
AU - Kistler,L
AU - Lepri,ST
AU - Livi,SA
AU - Louarn,P
AU - Owen,CJ
AU - Raines,JM
AU - Spitzer,SA
DO - 1538-4357/ae9153
PY - 2026///
SN - 0004-637X
TI - Resolving Compositional Features of Solar Wind Source Regions near the Heliospheric Current Sheet at 0.3 au
T2 - Astrophysical Journal
UR - http://dx.doi.org/10.3847/1538-4357/ae9153
VL - 1008
ER -