Ubiquitous Small-scale Dynamics in the Slow Solar Wind Formation Region Observed by Proba-3/ASPIICS

Abstract The origin of the slow solar wind remains a subject of ongoing debate. Several mechanisms have been proposed: the large expansion factor of open magnetic field in the corona, interchange reconnection between open and closed field lines in streamers and pseudostreamers, reconnection within the web of separatrices (S-web), and the field line pinch-off at streamer cusps. Many of these mechanisms involve the release of small-scale density inhomogeneities into the solar wind. A significant obstacle to understanding these processes is the difficulty of observing the region between the lower corona (traditionally observed with extreme ultraviolet imagers) and the high corona (traditionally observed with externally occulted coronagraphs), where these small-scale structures are thought to originate. Here, we present for the first time high-cadence (30 s) and high-spatial-resolution (5 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover> <mml:mrow> <mml:mo>.</mml:mo> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">″</mml:mi> </mml:mrow> </mml:mover> </mml:math> 6) white-light observations of the solar corona in the range of the radial distances r of 1.1 R ⊙ &lt; r &lt; 3 R ⊙ taken by the ASPIICS coronagraph on board the formation-flying Proba-3 mission. The ASPIICS data reveal ubiquitous, weak (0.5%–2% of the background brightness), small-scale dynamic features (blobs, outflows, inflows, jets, and waves). Their speeds range from 14 km s −1 to 520 km s −1 , with outflowing structures generally propagating faster than the inflowing ones. All these features appear to originate from streamers and pseudostreamers. ASPIICS observations provide important constraints on the role of small-scale dynamics in the formation of the slow solar wind.

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Journal
The Astrophysical Journal Letters
Published
2026-03-09
DOI
https://doi.org/10.3847/2041-8213/ae469b
Primary Topic
Solar and Space Plasma Dynamics
Type
article
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article

Ubiquitous Small-scale Dynamics in the Slow Solar Wind Formation Region Observed by Proba-3/ASPIICS

B. Nicula, S. V. Shestov, Laurent Dolla, L. Abbo et al.
The Astrophysical Journal Letters
Solar and Space Plasma Dynamics
article

Ubiquitous Small-scale Dynamics in the Slow Solar Wind Formation Region Observed by Proba-3/ASPIICS

B. Nicula, S. V. Shestov, Laurent Dolla, L. Abbo, M. Stȩślicki, F. Auchère, B. Bourgoignie, V. Andretta, S. Gunár, K. Tsinganos, M. Mierla, Jasmina Magdalenić, S. Giordano, L. Zangrilli, P. Rudawy, Damien Galano, Jorg Versluys, Christopje Jean, L. Rodriguez, B. Inhester, D. Berghmans, A. N. Zhukov, S. Fineschi, D. Beşliu-Ionescu, C. Aime, A. Debrabandere, H. Peter, Z. Zontou, R. Rougeot, C. Thizy, S. E. Gibson, P. Heinzel, B. D. Patel, P. Lamy, C. Marqué, D.-C. Talpeanu
article en

Abstract

Abstract The origin of the slow solar wind remains a subject of ongoing debate. Several mechanisms have been proposed: the large expansion factor of open magnetic field in the corona, interchange reconnection between open and closed field lines in streamers and pseudostreamers, reconnection within the web of separatrices (S-web), and the field line pinch-off at streamer cusps. Many of these mechanisms involve the release of small-scale density inhomogeneities into the solar wind. A significant obstacle to understanding these processes is the difficulty of observing the region between the lower corona (traditionally observed with extreme ultraviolet imagers) and the high corona (traditionally observed with externally occulted coronagraphs), where these small-scale structures are thought to originate. Here, we present for the first time high-cadence (30 s) and high-spatial-resolution (5 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mover> <mml:mrow> <mml:mo>.</mml:mo> </mml:mrow> <mml:mrow> <mml:mi mathvariant="normal">″</mml:mi> </mml:mrow> </mml:mover> </mml:math> 6) white-light observations of the solar corona in the range of the radial distances r of 1.1 R ⊙ &lt; r &lt; 3 R ⊙ taken by the ASPIICS coronagraph on board the formation-flying Proba-3 mission. The ASPIICS data reveal ubiquitous, weak (0.5%–2% of the background brightness), small-scale dynamic features (blobs, outflows, inflows, jets, and waves). Their speeds range from 14 km s −1 to 520 km s −1 , with outflowing structures generally propagating faster than the inflowing ones. All these features appear to originate from streamers and pseudostreamers. ASPIICS observations provide important constraints on the role of small-scale dynamics in the formation of the slow solar wind.

The Astrophysical Journal LettersVol. 999(2)
NSF National Center for Atmospheric Research (US), NSF NCAR High Altitude Observatory (US), Centrum Badań Kosmicznych (PL), Centre National de la Recherche Scientifique (FR), University of Liège (BE), Lomonosov Moscow State University (RU), National and Kapodistrian University of Athens (GR), University of Wrocław (PL), Royal Observatory of Belgium (BE), Czech Academy of Sciences, Astronomical Institute (CZ), Astronomical Observatory of Capodimonte (IT), Academia Oamenilor de Știință din România (RO), Institut d'Astrophysique Spatiale (FR), Osservatorio Astrofisico di Torino (IT), Max Planck Institute for Solar System Research (DE), Observatoire de la Côte d’Azur (FR), Laboratoire atmosphères, milieux, observations spatiales (FR), European Space Research and Technology Centre (NL), Romanian Academy (RO), KU Leuven (BE)
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