Alfvén wave solar model (AWSoM): Coronal heating

Journal Article · Thu Feb 20 00:00:00 EST 2014 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/782/2/81· OSTI ID:22351434

Van der Holst, B.; Sokolov, I. V.; Meng, X.; Jin, M.; Manchester, IV, W. B.; Tóth, G.; Gombosi, T. I. ^[1]

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1. Atmospheric, Oceanic, and Space Sciences, University of Michigan, Ann Arbor, MI 48109 (United States)

We present a new version of the Alfvén wave solar model, a global model from the upper chromosphere to the corona and the heliosphere. The coronal heating and solar wind acceleration are addressed with low-frequency Alfvén wave turbulence. The injection of Alfvén wave energy at the inner boundary is such that the Poynting flux is proportional to the magnetic field strength. The three-dimensional magnetic field topology is simulated using data from photospheric magnetic field measurements. This model does not impose open-closed magnetic field boundaries; those develop self-consistently. The physics include the following. (1) The model employs three different temperatures, namely the isotropic electron temperature and the parallel and perpendicular ion temperatures. The firehose, mirror, and ion-cyclotron instabilities due to the developing ion temperature anisotropy are accounted for. (2) The Alfvén waves are partially reflected by the Alfvén speed gradient and the vorticity along the field lines. The resulting counter-propagating waves are responsible for the nonlinear turbulent cascade. The balanced turbulence due to uncorrelated waves near the apex of the closed field lines and the resulting elevated temperatures are addressed. (3) To apportion the wave dissipation to the three temperatures, we employ the results of the theories of linear wave damping and nonlinear stochastic heating. (4) We have incorporated the collisional and collisionless electron heat conduction. We compare the simulated multi-wavelength extreme ultraviolet images of CR2107 with the observations from STEREO/EUVI and the Solar Dynamics Observatory/AIA instruments. We demonstrate that the reflection due to strong magnetic fields in the proximity of active regions sufficiently intensifies the dissipation and observable emission.

• OSTI ID: 22351434
• Journal Information: Astrophysical Journal, Vol. 782, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ACCELERATION
ANISOTROPY
CHROMOSPHERE
CYCLOTRON INSTABILITY
ELECTRON TEMPERATURE
EMISSION
EXTREME ULTRAVIOLET RADIATION
HELIOSPHERE
IMAGES
ION TEMPERATURE
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
REFLECTION
SIMULATION
SOLAR WIND
STAR MODELS
STOCHASTIC PROCESSES
SUN
THERMAL CONDUCTION
WAVELENGTHS