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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Autores principales: Vasquez, Alberto Marcos, Nuevo, Federico Alberto
Publicado: 2015
Materias:
magnetohydrodynamics (MHD)
methods: numerical
Sun: corona
Sun: heliosphere
techniques: spectroscopic
turbulence
Acceso en línea:https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0004637X_v806_n1_p_Oran
http://hdl.handle.net/20.500.12110/paper_0004637X_v806_n1_p_Oran
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) de Universidad de Buenos Aires
id paper:paper_0004637X_v806_n1_p_Oran
record_format dspace
spelling paper:paper_0004637X_v806_n1_p_Oran2023-06-08T14:29:14Z A STEADY-STATE PICTURE of SOLAR WIND ACCELERATION and CHARGE STATE COMPOSITION DERIVED from A GLOBAL WAVE-DRIVEN MHD MODEL Vasquez, Alberto Marcos Nuevo, Federico Alberto 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. 2015 https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0004637X_v806_n1_p_Oran 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
Vasquez, Alberto Marcos
Nuevo, Federico Alberto
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.
author Vasquez, Alberto Marcos
Nuevo, Federico Alberto
author_facet Vasquez, Alberto Marcos
Nuevo, Federico Alberto
author_sort Vasquez, Alberto Marcos
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
publishDate 2015
url https://bibliotecadigital.exactas.uba.ar/collection/paper/document/paper_0004637X_v806_n1_p_Oran
http://hdl.handle.net/20.500.12110/paper_0004637X_v806_n1_p_Oran
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AT nuevofedericoalberto asteadystatepictureofsolarwindaccelerationandchargestatecompositionderivedfromaglobalwavedrivenmhdmodel
AT vasquezalbertomarcos steadystatepictureofsolarwindaccelerationandchargestatecompositionderivedfromaglobalwavedrivenmhdmodel
AT nuevofedericoalberto steadystatepictureofsolarwindaccelerationandchargestatecompositionderivedfromaglobalwavedrivenmhdmodel
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