Near Subsonic Solar Wind Outflow from an Active Region

• DOI: 10.3847/1538-4357/ad57c4
• Publication Date: 2024-08-29T10:06:38Z
• Authors: Tamar Ervin; Stuart D. Bale; Samuel T. Badman; Trevor A. Bowen; Pete Riley; Kristoff Paulson; Yeimy J. Rivera; Orlando Romeo; Nikos Sioulas; Davin Larson; Jaye L. Verniero; Ryan M. Dewey; Jia Huang
• Keywords: Outflow; Polar wind

Abstract During Parker Solar Probe (Parker) Encounter 15 (E15), we observe an 18 hr period of near-subsonic ( M S ∼ 1) and sub-Alfvénic (SA), A ⋘ 1, slow-speed solar wind from 22 to 15.6 R ⊙ . As the most extreme SA interval measured date skirting sonic point, it is deepest has probed into formation acceleration region in corona. The stream also by Wind Magnetosonic Multiscale mission near 1 au at times consistent with ballistic propagation this slow stream. We investigate source, properties, potential coronal heating consequences via combining these observations modeling turbulence analysis. Through source mapping, situ evidence, multipoint arrival time considerations a candidate mass ejection, determine steady (nontransient), long-lived, approximately spiral aligned arises overexpanded field lines mapping back active region. Turbulence analysis Elsässer variables shows inertial range scaling z + mode f −3/2 ) be dominated slab component. discuss spectral flattening difficulties associated measuring − spectra, cautioning against making definitive conclusions mode. Despite being more than prior intervals, its turbulent nature does not appear qualitatively different previously observed streams. conclude that low-dynamic-pressure (which for space-weather conditions) large, structure spanning least au.