THE HEATING OF THE SOLAR CHROMOSPHERE, PLAGES, AND CORONA BY MAGNETOHYDRODYNAMIC WAVES

Journal Article · Fri Sep 01 04:00:00 EDT 1961 · Astrophysical Journal (U.S.)

DOI:https://doi.org/10.1086/147165· OSTI ID:4833299

Osterbrock, D E

The energy radiated from the chromosphere, corona, and upper chromosphere is estimated from observational data. The energy carried upwand by sound waves generated in the hydrogen convection zone is estimated and found sufficient to balance these losses, though the numerical result is uncertain because of its dependence on the turbulent velocity field. The spectrum of this noise is a broad band with maximum near the frequency of 0.01 cps. The waves propagate in the fast mode and become increasingly magnetohydrodynamic in the chromosphere, because of the negative density gradient. Little, if any, energy is emitted by the hydrogen convection zone in the slow or Alfven modes, and these modes are strongly absorbed in the photesphere. The cross-section for collisions between neutral atoms and ions in the chromosphere is large, and the dissipation of the fast-mode waves by the frictional damping mechanism is very small. The waves build up to shocks, and the dissipation of these shocks is the main energy source for the chromosphere. The dissipation of the shocks is in a way analogous to the Brinkley-Kirkwood theory of the dissipation of pure gas-dynamic shocks. At great heights, where the magnetic field dominates, the shocks become weaker, the dissipation decreases, and the rays are refracted back down~ard toward the photosphere. However, at these heights, collisions between shocks must the Alfven mode, and these modes then propagate straight up the magnetic line of force, with essentially no weakening by refraction, and carry energy intop the corona. The plages are regions of larger magnetic field, where there is extra generation of noise in the hydrogen convection zone below and where the refraction and shock-collision effects are more important. The spicules seen at the limb of the sun are interpreted as slow-mode disturbances carrying chromospheric material up along the magnetic lines of force into the corona. (auth)

• Research Organization: Institute for Advanced Study, Princeton, N.J.
• NSA Number: NSA-15-031456
• OSTI ID: 4833299
• Journal Information: Astrophysical Journal (U.S.), Journal Name: Astrophysical Journal (U.S.) Vol. Vol: 134; ISSN ASJOA
• Country of Publication: Country unknown/Code not available
• Language: English

Related Subjects

ABSORPTION
ALFVEN WAVES
ASTROPHYSICS
COLLISIONS
CONVECTION
CORONA
CROSS SECTIONS
DENSITY
DISTRIBUTION
DISTURBANCES
ENERGY
FREQUENCY
GASES
HEATING
HYDROGEN
LEVELS
LOSSES
MAGNETIC FIELDS
MAGNETOHYDRODYNAMICS
MOTION
NUMERICALS
PHOTOSPHERE
PHYSICS
PLASMA WAVES
RADIATIONS
REFRACTION
SHOCK WAVES
SOUND
SUN
TURBULENCE
VELOCITY