A Semiempirical Magnetohydrodynamical Model of the Solar Wind

Cohen, Ofer; Соколов, И. В.; Roussev, I. I.; Arge, C. N.; Manchester, W.; Gombosi, T. I.; Frazin, R. A.; Park, H.; Butala, Mark D.; Kamalabadi, F.; Velli, M.

doi:10.1086/511154

Cited by 169 publications

(227 citation statements)

References 26 publications

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“…The physics of this domain is described by the equations of MHD, with additional source terms required to take into account the heating and acceleration of the solar wind (Groth et al 2000;Usmanov et al 2000). Recently, Cohen et al (2007) developed a solar wind model based on the empirical relationship between solar wind speed and magnetic flux tube expansion (Wang & Sheeley 1990), which has been incorporated into the SWMF. Here we use the coronal model presented in Roussev et al (2003b).…”

Section: Numerical Methods: Swmf and Bats-r-usmentioning

confidence: 99%

Three‐dimensional MHD Simulation of the 2003 October 28 Coronal Mass Ejection: Comparison with LASCO Coronagraph Observations

Manchester

Vourlidas

Tóth

et al. 2008

Astrophysical Journal

155

118

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We numerically model the coronal mass ejection (CME) event of 2003 October 28 that erupted from AR 10486 and propagated to Earth in less than 20 hr, causing severe geomagnetic storms. The magnetohydrodynamic (MHD) model is formulated by first arriving at a steady state corona and solar wind employing synoptic magnetograms. We initiate two CMEs from the same active region, one approximately a day earlier that preconditions the solar wind for the much faster CME on the 28th. This second CME travels through the corona at a rate of over 2500 km s À1 , driving a strong forward shock. We clearly identify this shock in an image produced by the Large Angle Spectrometric Coronagraph (LASCO) C3 and reproduce the shock and its appearance in synthetic white-light images from the simulation. We find excellent agreement with both the general morphology and the quantitative brightness of the model CME with LASCO observations. These results demonstrate that the CME shape is largely determined by its interaction with the ambient solar wind and may not be sensitive to the initiation process. We then show how the CME would appear as observed by wide-angle coronagraphs on board the Solar Terrestrial Relations Observatory (STEREO) spacecraft. We find complex time evolution of the white-light images as a result of the way in which the density structures pass through the Thomson sphere. The simulation is performed with the Space Weather Modeling Framework (SWMF).

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Section: Numerical Methods: Swmf and Bats-r-usmentioning

confidence: 99%

Three‐dimensional MHD Simulation of the 2003 October 28 Coronal Mass Ejection: Comparison with LASCO Coronagraph Observations

Manchester

Vourlidas

Tóth

et al. 2008

Astrophysical Journal

155

118

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“…The most up to date models are fully three dimensional and self-consistent (Vidotto et al 2009(Vidotto et al , 2012 and use more physically motivated arguments to determine mass loss rates (Holzwarth & Jardine 2007;Cohen et al 2007;Cranmer & Saar 2011). However many assumptions are used and scaling relations are still present in some models.…”

Section: Stellar Wind Modelsmentioning

confidence: 99%

The effects of stellar winds on the magnetospheres and potential habitability of exoplanets

See

Jardine

Vidotto

et al. 2014

A&A

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Context. The principle definition of habitability for exoplanets is whether they can sustain liquid water on their surfaces, i.e. that they orbit within the habitable zone. However, the planet's magnetosphere should also be considered, since without it, an exoplanet's atmosphere may be eroded away by stellar winds. Aims. The aim of this paper is to investigate magnetospheric protection of a planet from the effects of stellar winds from solar-mass stars. Methods. We study hypothetical Earth-like exoplanets orbiting in the host star's habitable zone for a sample of 124 solar-mass stars. These are targets that have been observed by the Bcool Collaboration. Using two wind models, we calculate the magnetospheric extent of each exoplanet. These wind models are computationally inexpensive and allow the community to quickly estimate the magnetospheric size of magnetised Earth-analogues orbiting cool stars. Results. Most of the simulated planets in our sample can maintain a magnetosphere of ∼5 Earth radii or larger. This suggests that magnetised Earth analogues in the habitable zones of solar analogues are able to protect their atmospheres and is in contrast to planets around young active M dwarfs. In general, we find that Earth-analogues around solar-type stars, of age 1.5 Gyr or older, can maintain at least a Paleoarchean Earth sized magnetosphere. Our results indicate that planets around 0.6-0.8 solar-mass stars on the low activity side of the Vaughan-Preston gap are the optimum observing targets for habitable Earth analogues.

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“…This code has previously been used to model both the solar corona (Groth et al 2000;Roussev et al 2003b;Cohen et al 2007;van der Holst et al 2010) and CMEs (e.g., Groth et al 2000;Manchester et al 2004;Roussev et al 2003a;Tóth et al 2007;van der Holst et al 2009), and has recently been greatly advanced for the purpose of simulating highenergy, high-density laser experiments . The MHD system of equations given below comprises the coronal model (as given in van der and is solved with the BATS-R-US code:…”

Section: System Of Equationsmentioning

confidence: 99%

“…CMEs have typically been simulated with single-fluid three-dimensional (3D) magnetohydrodynamical (MHD) models that address only the thermodynamics of the ion species, and assume that the electrons must be of the same temperature. The thermodynamics of the corona for these models have been addressed with empirical heating functions (Groth et al 2000) or a variable adiabatic index (Wu et al 1999;Roussev et al 2003b;Cohen et al 2007). An examination of the temperature structure resulting from a CME-driven shock simulated with the coronal model of Groth et al (2000) is found in Manchester et al (2004).…”

Section: Introductionmentioning

confidence: 99%

The Coupled Evolution of Electrons and Ions in Coronal Mass Ejection-Driven Shocks

Manchester

Holst

Tóth

et al. 2012

ApJ

Self Cite

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We present simulations of coronal mass ejections (CMEs) performed with a new two-temperature coronal model developed at the University of Michigan, which is able to address the coupled thermodynamics of the electron and proton populations in the context of a single fluid. This model employs heat conduction for electrons, constant adiabatic index (γ = 5/3), and includes Alfvén wave pressure to accelerate the solar wind. The Wang-Sheeley-Arge empirical model is used to determine the Alfvén wave pressure necessary to produce the observed bimodal solar wind speed. The Alfvén waves are dissipated as they propagate from the Sun and heat protons on open magnetic field lines to temperatures above 2 MK. The model is driven by empirical boundary conditions that includes GONG magnetogram data to calculate the coronal field, and STEREO/EUVI observations to specify the density and temperature at the coronal boundary by the Differential Emission Measure Tomography method. With this model, we simulate the propagation of fast CMEs and study the thermodynamics of CME-driven shocks. Since the thermal speed of the electrons greatly exceeds the speed of the CME, only protons are directly heated by the shock. Coulomb collisions low in the corona couple the protons and electrons allowing heat exchange between the two species. However, the coupling is so brief that the electrons never achieve more than 10% of the maximum temperature of the protons. We find that heat is able to conduct on open magnetic field lines and rapidly propagates ahead of the CME to form a shock precursor of hot electrons.

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A Semiempirical Magnetohydrodynamical Model of the Solar Wind

Cited by 169 publications

References 26 publications

Three‐dimensional MHD Simulation of the 2003 October 28 Coronal Mass Ejection: Comparison with LASCO Coronagraph Observations

Three‐dimensional MHD Simulation of the 2003 October 28 Coronal Mass Ejection: Comparison with LASCO Coronagraph Observations

The effects of stellar winds on the magnetospheres and potential habitability of exoplanets

The Coupled Evolution of Electrons and Ions in Coronal Mass Ejection-Driven Shocks

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