Journal article
Differentiating the Acceleration Mechanisms in the Slow and Alfvénic Slow Solar Wind
The Astrophysical journal, Vol.980(1), 70
02/10/2025
DOI: 10.3847/1538-4357/ada699
Abstract
In the corona, plasma is accelerated to hundreds of kilometers per second and heated to temperatures hundreds of times hotter than the Sun's surface before it escapes to form the solar wind. Decades of space-based experiments have shown that the energization process does not stop after it escapes. Instead, the solar wind continues to accelerate, and it cools far more slowly than a freely expanding adiabatic gas. Recent work suggests that fast solar wind requires additional momentum beyond what can be provided by the observed thermal pressure gradients alone, whereas it is sufficient for the slowest wind. The additional acceleration for fast wind can be provided through an Alfvén wave pressure gradient. Beyond this fast/slow categorization, however, a subset of slow solar wind exhibits high Alfvénicity that suggests that Alfvén waves could play a larger role in its acceleration compared to conventional slow wind outflows. Through a well-timed conjunction between Solar Orbiter and Parker Solar Probe (PSP), we trace the energetics of slow wind to compare with a neighboring Alfvénic slow solar wind stream. An analysis that integrates remote and heliospheric properties and modeling of the two distinct solar wind streams finds that Alfvénic slow solar wind behaves like fast wind, where a wave pressure gradient is required to reconcile its full acceleration, while non-Alfvénic slow wind can be driven by its nonadiabatic electron and proton thermal pressure gradients. Derived coronal conditions of the source region indicate good model compatibility, but extended coronal observations are required to effectively trace solar wind energetics below PSP's orbit.
Details
- Title: Subtitle
- Differentiating the Acceleration Mechanisms in the Slow and Alfvénic Slow Solar Wind
- Creators
- Yeimy J. Rivera - Center for Astrophysics ∣ Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USASamuel T. Badman - Center for Astrophysics ∣ Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USAJ. L. Verniero - Goddard Space Flight CenterTania Varesano - University of Colorado BoulderMichael L. Stevens - Center for Astrophysics ∣ Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USAJulia E. Stawarz - Northumbria UniversityKatharine K. Reeves - Center for Astrophysics ∣ Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USAJim M. Raines - University of Michigan Department of Climate & Space Sciences & Engineering, 2455 Hayward Street, Ann Arbor, MI 48109-2143, USAJohn C. Raymond - Center for Astrophysics ∣ Harvard & Smithsonian , 60 Garden Street, Cambridge, MA 02138, USAChristopher J. Owen - University College London Mullard Space Science Laboratory, Holmbury St. Mary, Dorking, Surrey, RH5 6NT, UKStefano A. Livi - Southwest Research InstituteSusan T. Lepri - University of Michigan Department of Climate & Space Sciences & Engineering, 2455 Hayward Street, Ann Arbor, MI 48109-2143, USAEnrico Landi - University of Michigan Department of Climate & Space Sciences & Engineering, 2455 Hayward Street, Ann Arbor, MI 48109-2143, USAJasper. S. Halekas - University of Iowa Department of Physics and Astronomy, Iowa City, IA 52242, USATamar Ervin - University of California, BerkeleyRyan M. Dewey - University of Michigan Department of Climate & Space Sciences & Engineering, 2455 Hayward Street, Ann Arbor, MI 48109-2143, USARossana De Marco - INAF—Institute for Space Astrophysics and Planetology , Rome, ItalyRaffaella D’Amicis - INAF—Institute for Space Astrophysics and Planetology , Rome, ItalyJean-Baptiste Dakeyo - Observatoire Midi-PyrénéesStuart D. Bale - University of California, BerkeleyB. L. Alterman - Goddard Space Flight Center
- Resource Type
- Journal article
- Publication Details
- The Astrophysical journal, Vol.980(1), 70
- Publisher
- The American Astronomical Society
- DOI
- 10.3847/1538-4357/ada699
- ISSN
- 0004-637X
- eISSN
- 1538-4357
- Number of pages
- 16
- Grant note
- NNN06AA01C / NASA ∣ Science Mission Directorate (SMD) (https://doi.org/10.13039/100016465)
- Language
- English
- Date published
- 02/10/2025
- Academic Unit
- Physics and Astronomy
- Record Identifier
- 9984790974402771
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