Magnetohydrodynamic Waves and Coronal Heating: Unifying Empirical and MHD Turbulence Models

Соколов, И. В.; Holst, B. van der; Oran, R.; Downs, Cooper; Roussev, I. I.; Jin, Meng; Manchester, W.; Evans, R. M.; Gombosi, T. I.

doi:10.1088/0004-637x/764/1/23

Cited by 181 publications

(239 citation statements)

References 51 publications

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“…This will be considered in a future study, incorporating the recovered ZDI magnetic field maps into a detailed 3D magnetohydrodynamics (MHD) code (BATS-R-US, Powell et al 1999;Tóth et al 2012), which was originally developed and validated for the solar wind and corona (e.g. Sokolov et al 2013;van der Holst et al 2014) and recently applied in the stellar context (e.g. ).…”

Section: Summary and Discussionmentioning

confidence: 99%

Activity and magnetic field structure of the Sun-like planet-hosting star HD 1237

Alvarado‐Gómez

Hussain

Grunhut

et al. 2015

A&A

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We analyse the magnetic activity characteristics of the planet-hosting Sun-like star, HD 1237, using HARPS spectro-polarimetric time-series data. We find evidence of rotational modulation of the magnetic longitudinal field measurements that is consistent with our ZDI analysis with a period of 7 days. We investigate the effect of customising the LSD mask to the line depths of the observed spectrum and find that it has a minimal effect on the shape of the extracted Stokes V profile but does result in a small increase in the S/N (∼7%). We find that using a Milne-Eddington solution to describe the local line profile provides a better fit to the LSD profiles in this slowly rotating star, which also affects the recovered ZDI field distribution. We also introduce a fit-stopping criterion based on the information content (entropy) of the ZDI map solution set. The recovered magnetic field maps show a strong (+90 G) ring-like azimuthal field distribution and a complex radial field dominating at mid latitudes (∼45 degrees). Similar magnetic field maps are recovered from data acquired five months apart. Future work will investigate how this surface magnetic field distribution affeccts the coronal magnetic field and extended environment around this planet-hosting star.

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Section: Summary and Discussionmentioning

confidence: 99%

Activity and magnetic field structure of the Sun-like planet-hosting star HD 1237

Alvarado‐Gómez

Hussain

Grunhut

et al. 2015

A&A

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“…The computational domain is based on a non-uniform spherical grid which allows us to treat the sharp gradients in the transition region as well as resolve the heliospheric current sheet. The model employs a unified approach for treating turbulent dissipation in both open and closed magnetic field lines, as presented in Sokolov et al (2013). AWSoM was described in detail and validated in Oran et al (2013).…”

Section: Awsom Model Descriptionmentioning

confidence: 99%

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

Oran¹,

Landi

Holst

et al. 2017

ApJ

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In the present work, we test the predictions of the AWSoM model, a global extended-MHD model capable of calculating the propagation and turbulent dissipation of Alfvén waves in any magnetic topology, against high resolution spectra of the quiescent off-disk solar corona. Wave dissipation is the only heating mechanism assumed in this model. Combining 3D model results with the CHIANTI atomic database, we were able to create synthetic line-of-sight spectra which include the effects of emission line broadening due to both thermal and wave-related non-thermal motions. To the best of our knowledge this is the first time a global model is used to obtain synthetic non-thermal line broadening. We obtained a steady-state solution driven by a synoptic magnetogram and compared the synthetic spectra with SUMER observations of a quiescent area above the solar west limb extending between 1.04 and 1.34 solar radii at the equator. Both the predicted line widths and the total line fluxes were consistent with the observations for 5 different ions. Using the 3D solution, we were able to locate the region that contributes the most to the emission used for measuring electron properties; we found that region to be a pseudo-streamer, whose modeled electron temperature and density are consistent with the measured ones. We conclude that the turbulent dissipation assumed in the AWSoM model can simultaneously account for the observed heating rate and the non-dissipated wave energy observed in this region.

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“…In particular, when trying to model the energy gain and temperature decoupling of electrons and protons, a one-fluid, two-temperature ideal MHD model can be used to retrieve information for comparison with observations. This has been successfully done by other authors (see, e.g., van der Holst et al 2010, Sokolov et al 2013) aiming at modeling the solar environment as accurately as possible, thus including many additional or observationdriven terms in the standard MHD equations. This introduces the necessary physics (such as particle collisions, Alfvén waves heating, etc.…”

Section: Modeling Approachmentioning

confidence: 99%

Plasma Physical Parameters Along Cme-Driven Shocks. Ii. Observation–simulation Comparison

Bacchini

Susino

Бемпорад

et al. 2015

ApJ

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In this work, we compare the spatial distribution of the plasma parameters along the 1999 June 11 coronal mass ejection (CME)-driven shock front with the results obtained from a CME-like event simulated with the FLIPMHD3D code, based on the FLIP-MHD particle-in-cell method. The observational data are retrieved from the combination of white-light coronagraphic data (for the upstream values) and the application of the RankineHugoniot equations (for the downstream values). The comparison shows a higher compression ratio X and Alfvénic Mach number M A at the shock nose, and a stronger magnetic field deflection d toward the flanks, in agreement with observations. Then, we compare the spatial distribution of M A with the profiles obtained from the solutions of the shock adiabatic equation relating M A , X, and Bn q (the angle between the upstream magnetic field and the shock front normal) for the special cases of parallel and perpendicular shock, and with a semi-empirical expression for a generically oblique shock. The semi-empirical curve approximates the actual values of M A very well, if the effects of a non-negligible shock thickness sh d and plasma-to magnetic pressure ratio u b are taken into account throughout the computation. Moreover, the simulated shock turns out to be supercritical at the nose and sub-critical at the flanks. Finally, we develop a new one-dimensional Lagrangian ideal MHD method based on the GrAALE code, to simulate the ion-electron temperature decoupling due to the shock transit. Two models are used, a simple solar wind model and a variable-γ model. Both produce results in agreement with observations, the second one being capable of introducing the physics responsible for the additional electron heating due to secondary effects (collisions, Alfvén waves, etc.).

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Magnetohydrodynamic Waves and Coronal Heating: Unifying Empirical and MHD Turbulence Models

Cited by 181 publications

References 51 publications

Activity and magnetic field structure of the Sun-like planet-hosting star HD 1237

Activity and magnetic field structure of the Sun-like planet-hosting star HD 1237

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

Plasma Physical Parameters Along Cme-Driven Shocks. Ii. Observation–simulation Comparison

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