A STEADY-STATE PICTURE of SOLAR WIND ACCELERATION and CHARGE STATE COMPOSITION DERIVED from A GLOBAL WAVE-DRIVEN MHD MODEL
he higher charge states found in slow (<400 km s-1) solar wind streams compared to fast streams have supported the hypothesis that the slow wind originates in closed coronal loops and is released intermittently through reconnection. Here we examine whether a highly ionized slow wind can also...
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todo:paper_0004637X_v806_n1_p_Oran2023-10-03T14:02:37Z A STEADY-STATE PICTURE of SOLAR WIND ACCELERATION and CHARGE STATE COMPOSITION DERIVED from A GLOBAL WAVE-DRIVEN MHD MODEL Oran, R. Landi, E. Holst, B.V.D. Lepri, S.T. Vásquez, A.M. Nuevo, F.A. Frazin, R. Manchester, W. Sokolov, I. Gombosi, T.I. magnetohydrodynamics (MHD) methods: numerical Sun: corona Sun: heliosphere techniques: spectroscopic turbulence he higher charge states found in slow (<400 km s-1) solar wind streams compared to fast streams have supported the hypothesis that the slow wind originates in closed coronal loops and is released intermittently through reconnection. Here we examine whether a highly ionized slow wind can also form along steady and open magnetic field lines. We model the steady-state solar atmosphere using the Alfvén Wave Solar Model (AWSoM), a global MHD model driven by Alfvén waves, and apply an ionization code to calculate the charge state evolution along modeled open field lines. This constitutes the first charge state calculation covering all latitudes in a realistic magnetic field. The ratios and are compared to in situ Ulysses observations and are found to be higher in the slow wind, as observed; however, they are underpredicted in both wind types. The modeled ion fractions of S, Si, and Fe are used to calculate line-of-sight intensities, which are compared to Extreme-ultraviolet Imaging Spectrometer (EIS) observations above a coronal hole. The agreement is partial and suggests that all ionization rates are underpredicted. Assuming the presence of suprathermal electrons improved the agreement with both EIS and Ulysses observations; importantly, the trend of higher ionization in the slow wind was maintained. The results suggest that there can be a sub-class of slow wind that is steady and highly ionized. Further analysis shows that it originates from coronal hole boundaries (CHBs), where the modeled electron density and temperature are higher than inside the hole, leading to faster ionization. This property of CHBs is global and observationally supported by EUV tomography. © 2015. The American Astronomical Society. All rights reserved. Fil:Vásquez, A.M. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. Fil:Nuevo, F.A. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_0004637X_v806_n1_p_Oran |
| institution |
Universidad de Buenos Aires |
| institution_str |
I-28 |
| repository_str |
R-134 |
| collection |
Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| topic |
magnetohydrodynamics (MHD) methods: numerical Sun: corona Sun: heliosphere techniques: spectroscopic turbulence |
| spellingShingle |
magnetohydrodynamics (MHD) methods: numerical Sun: corona Sun: heliosphere techniques: spectroscopic turbulence Oran, R. Landi, E. Holst, B.V.D. Lepri, S.T. Vásquez, A.M. Nuevo, F.A. Frazin, R. Manchester, W. Sokolov, I. Gombosi, T.I. A STEADY-STATE PICTURE of SOLAR WIND ACCELERATION and CHARGE STATE COMPOSITION DERIVED from A GLOBAL WAVE-DRIVEN MHD MODEL |
| topic_facet |
magnetohydrodynamics (MHD) methods: numerical Sun: corona Sun: heliosphere techniques: spectroscopic turbulence |
| description |
he higher charge states found in slow (<400 km s-1) solar wind streams compared to fast streams have supported the hypothesis that the slow wind originates in closed coronal loops and is released intermittently through reconnection. Here we examine whether a highly ionized slow wind can also form along steady and open magnetic field lines. We model the steady-state solar atmosphere using the Alfvén Wave Solar Model (AWSoM), a global MHD model driven by Alfvén waves, and apply an ionization code to calculate the charge state evolution along modeled open field lines. This constitutes the first charge state calculation covering all latitudes in a realistic magnetic field. The ratios and are compared to in situ Ulysses observations and are found to be higher in the slow wind, as observed; however, they are underpredicted in both wind types. The modeled ion fractions of S, Si, and Fe are used to calculate line-of-sight intensities, which are compared to Extreme-ultraviolet Imaging Spectrometer (EIS) observations above a coronal hole. The agreement is partial and suggests that all ionization rates are underpredicted. Assuming the presence of suprathermal electrons improved the agreement with both EIS and Ulysses observations; importantly, the trend of higher ionization in the slow wind was maintained. The results suggest that there can be a sub-class of slow wind that is steady and highly ionized. Further analysis shows that it originates from coronal hole boundaries (CHBs), where the modeled electron density and temperature are higher than inside the hole, leading to faster ionization. This property of CHBs is global and observationally supported by EUV tomography. © 2015. The American Astronomical Society. All rights reserved. |
| format |
JOUR |
| author |
Oran, R. Landi, E. Holst, B.V.D. Lepri, S.T. Vásquez, A.M. Nuevo, F.A. Frazin, R. Manchester, W. Sokolov, I. Gombosi, T.I. |
| author_facet |
Oran, R. Landi, E. Holst, B.V.D. Lepri, S.T. Vásquez, A.M. Nuevo, F.A. Frazin, R. Manchester, W. Sokolov, I. Gombosi, T.I. |
| author_sort |
Oran, R. |
| title |
A STEADY-STATE PICTURE of SOLAR WIND ACCELERATION and CHARGE STATE COMPOSITION DERIVED from A GLOBAL WAVE-DRIVEN MHD MODEL |
| title_short |
A STEADY-STATE PICTURE of SOLAR WIND ACCELERATION and CHARGE STATE COMPOSITION DERIVED from A GLOBAL WAVE-DRIVEN MHD MODEL |
| title_full |
A STEADY-STATE PICTURE of SOLAR WIND ACCELERATION and CHARGE STATE COMPOSITION DERIVED from A GLOBAL WAVE-DRIVEN MHD MODEL |
| title_fullStr |
A STEADY-STATE PICTURE of SOLAR WIND ACCELERATION and CHARGE STATE COMPOSITION DERIVED from A GLOBAL WAVE-DRIVEN MHD MODEL |
| title_full_unstemmed |
A STEADY-STATE PICTURE of SOLAR WIND ACCELERATION and CHARGE STATE COMPOSITION DERIVED from A GLOBAL WAVE-DRIVEN MHD MODEL |
| title_sort |
steady-state picture of solar wind acceleration and charge state composition derived from a global wave-driven mhd model |
| url |
http://hdl.handle.net/20.500.12110/paper_0004637X_v806_n1_p_Oran |
| work_keys_str_mv |
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