Alfvén Wave Turbulence as a Coronal Heating Mechanism: Simultaneously Predicting the Heating Rate and the Wave-induced Emission Line Broadening

Oran, R.; Landi, E.; Holst, B. van der; Соколов, И. В.; Gombosi, T. I.

doi:10.3847/1538-4357/aa7fec

Cited by 42 publications

(58 citation statements)

References 89 publications

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“…In order to explain the fast wind component, an additional momentum term is required (Usmanov et al ., 2000; Airapetian et al ., 2010; Ofman, 2010; Airapetian and Cuntz, 2015). Recently developed data-driven global MHD models can successfully reproduce the overall global structure of the solar corona, the solar wind and incorporate the physical processes of heating and acceleration of the solar wind with the initial state and boundary conditions directly derived from observations (van der Holst et al ., 2014; Oran et al ., 2017; Reiss et al ., 2019).…”

Section: Drivers and Signatures Of Space Weather From The Sunmentioning

confidence: 99%

Impact of space weather on climate and habitability of terrestrial-type exoplanets

Airapetian

Barnes

Cohen

et al. 2019

International Journal of Astrobiology

193

141

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The search for life in the Universe is a fundamental problem of astrobiology and modern science. The current progress in the detection of terrestrial-type exoplanets has opened a new avenue in the characterization of exoplanetary atmospheres and in the search for biosignatures of life with the upcoming ground-based and space missions. To specify the conditions favourable for the origin, development and sustainment of life as we know it in other worlds, we need to understand the nature of global (astrospheric), and local (atmospheric and surface) environments of exoplanets in the habitable zones (HZs) around G-K-M dwarf stars including our young Sun. Global environment is formed by propagated disturbances from the planet-hosting stars in the form of stellar flares, coronal mass ejections, energetic particles and winds collectively known as astrospheric space weather. Its characterization will help in understanding how an exoplanetary ecosystem interacts with its host star, as well as in the specification of the physical, chemical and biochemical conditions that can create favourable and/or detrimental conditions for planetary climate and habitability along with evolution of planetary internal dynamics over geological timescales. A key linkage of (astro)physical, chemical and geological processes can only be understood in the framework of interdisciplinary studies with the incorporation of progress in heliophysics, astrophysics, planetary and Earth sciences. The assessment of the impacts of host stars on the climate and habitability of terrestrial (exo)planets will significantly expand the current definition of the HZ to the biogenic zone and provide new observational strategies for searching for signatures of life. The major goal of this paper is to describe and discuss the current status and recent progress in this interdisciplinary field in light of presentations and discussions during the NASA Nexus for Exoplanetary System Science funded workshop ‘Exoplanetary Space Weather, Climate and Habitability’ and to provide a new roadmap for the future development of the emerging field of exoplanetary science and astrobiology.

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Section: Drivers and Signatures Of Space Weather From The Sunmentioning

confidence: 99%

Impact of space weather on climate and habitability of terrestrial-type exoplanets

Airapetian

Barnes

Cohen

et al. 2019

International Journal of Astrobiology

193

141

View full text Add to dashboard Cite

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“…These include how their additional equations are derived, how they relate the energy in the subgrid‐scale turbulence to shear in the shortest‐scale fluctuations of their mean flow solution, their estimates of the energy dissipation rates feeding turbulent energy back into the plasmas internal energy, and the way the Alfvén wave energy fluxes are set at the inner boundary of the models. These modified codes do compare successfully with the general character of the observed corona and solar wind (Downs et al, ; Meng et al, ; Oran et al, ; Usmanov et al, ). While these developments represent a significant step toward a more complete self‐consistent physical model, they are based on a description of the turbulence, which is greatly simplified.…”

Section: Assessment Of Current Model Capabilitiesmentioning

confidence: 83%

Assessing the Quality of Models of the Ambient Solar Wind

et al. 2018

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In this paper we present an assessment of the status of models of the global solar wind in the inner heliosphere. We limit our discussion to the class of models designed to provide solar wind forecasts, excluding those designed for the purpose of testing physical processes in idealized configurations. In addition, we limit our discussion to modeling of the ambient wind in the absence of coronal mass ejections. In this assessment we cover use of the models both in forecast mode and as tools for scientific research. We present a brief history of the development of these models, discussing the range of physical approximations in use. We discuss the limitations of the data inputs available to these models and its impact on their quality. We also discuss current model development trends. Empirical ModelsModeling of the solar coronal magnetic field began in earnest in the early 1960s with the advent of computers and the availability of photospheric magnetograms. The earliest models of the inner coronal field were based

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“…Apart from the damping, reflections of wave due to density stratification is also expected in our simulation. The reflection of Alfvén wave energy due to gravitational stratification leading to the levelling-off non-thermal line widths is reported in Oran et al (2017). The detailed mechanism of wave reflection and its effect on the variation of the non-thermal line widths in our simulations is beyond the focus of the current study and will be explored in the future.…”

Section: Energy Estimatementioning

confidence: 91%

“…The estimated energy flux was found to be just enough to balance the energy losses in the polar open-field regions of the solar corona. Additionally, several 1D (Lau & Siregar 1996;Orta et al 2003;Suzuki & Inutsuka 2006;Cranmer et al 2007;Oran et al 2013;van der Holst et al 2014;Oran et al 2017), 2.5D Davila 1997b, 1998), and3D (using reduced MHD;van Ballegooijen et al 2011van Ballegooijen et al , 2017 wave-based models driven purely by Alfvén waves have been somewhat successful in explaining the large non-thermal widths of coronal emission lines and acceleration of fast solar winds in open and closed magnetic field regions.…”

Section: Introductionmentioning

confidence: 99%

Investigating “Dark” Energy in the Solar Corona Using Forward Modeling of MHD Waves

Pant¹,

Magyar²,

Doorsselaere³

et al. 2019

ApJ

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It is now well established that the Alfvénic waves are ubiquitous in the solar corona. However, the Alfvénic wave energy estimated from the Doppler velocity measurements in the corona was found to be four orders of magnitude less than that estimated from non-thermal line widths. McIntosh & De Pontieu (2012) suggested that this discrepancy in energy might be due to the line-of-sight (LOS) superposition of the several oscillating structures, which can lead to an underestimation of the Alfvénic wave amplitudes and energies. McIntosh & De Pontieu (2012) termed this coronal 'dark' or 'hidden' energy. However, their simulations required the use of an additional, unknown source of Alfvénic wave energy to provide agreement with measurements of the coronal non-thermal line widths. In this study, we investigate the requirement of this unknown source of additional 'dark' energy in the solar corona using gravitationally stratified 3D magnetohydrodynamic (MHD) simulations of propagating waves. We excite the transverse MHD waves and generate synthetic observations for the Fe XIII emission line. We establish that the LOS superposition greatly reduces the Doppler velocity amplitudes and increases the non-thermal line widths. Importantly, our model generates the observed wedge-shaped correlation between Doppler velocities and non-thermal line widths. We find that the observed wave energy is only 0.2-1% of the true wave energy which explains 2-3 orders of magnitude of the energy discrepancy. We conclusively establish that the true wave energies are hidden in the non-thermal line widths. Hence, our results rule out the requirement for an additional 'dark' energy in the solar corona.

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Alfvén Wave Turbulence as a Coronal Heating Mechanism: Simultaneously Predicting the Heating Rate and the Wave-induced Emission Line Broadening

Cited by 42 publications

References 89 publications

Impact of space weather on climate and habitability of terrestrial-type exoplanets

Impact of space weather on climate and habitability of terrestrial-type exoplanets

Assessing the Quality of Models of the Ambient Solar Wind

Investigating “Dark” Energy in the Solar Corona Using Forward Modeling of MHD Waves

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