scholarly journals Recent Advances in Acoustic Heating

1990 ◽  
Vol 142 ◽  
pp. 231-235
Author(s):  
P. Ulmschneider
Keyword(s):  
Shock Waves ◽  
Solar Atmosphere ◽  
Acoustic Waves ◽  
Radiation Loss ◽  
Rotating Stars ◽  
Magnetic Heating ◽  
Surface Variation ◽  
Chromospheric Emission ◽  
Surface Convection ◽  
Chromospheric Heating

Turbulent surface convection zones of stars generate acoustic waves which contribute to the heating of chromospheres and coronae. The dissipation of limiting strength acoustic shock waves agrees well with the empirically determined chromospheric radiation loss rates. Acoustic waves with frequency and energy required for the chromospheric heating are observed in the solar atmosphere. Acoustic heating can explain the basal chromospheric emission of slowly rotating stars and constitutes a weak background in faster rotating stars; it can not explain the emission-rotation correlation and the surface variation of emission which are due to magnetic heating.

scholarly journals Acceleration, Containment and Emission of High Energy Flare Particles: Radio Evidence

1974 ◽  
Vol 57 ◽  
pp. 423-435 ◽  
Author(s):  
A. Boischot
Keyword(s):  
Shock Wave ◽  
Shock Waves ◽  
Solar Atmosphere ◽  
Impulsive Phase ◽  
High Energy ◽  
Continuous Phase ◽  
List Type ◽  
Radio Bursts ◽  
Type Ii ◽  
Type Number

The existence of non thermal radio bursts provide evidences for the acceleration of electrons in the solar atmosphere.It is shown, from the characteristics of the bursts, that the electrons are accelerated in at least four different phases: (1)An impulsive phase which gives μib and III bursts.(2)A gradual phase which gives μIV and S1IV bursts.(3)A quasi-continuous phase which gives S2IV bursts and noise storms.(4)An acceleration by shock waves gives type II bursts.(5)Eventually, another shock-wave acceleration giving the moIV burst.

On frequency and strength of shock waves in the solar atmosphere

Solar Physics ◽  
1970 ◽  
Vol 12 (3) ◽  
pp. 403-415 ◽  
Author(s):  
Peter Ulmschneider
Keyword(s):  
Shock Waves ◽  
Solar Atmosphere

Magnetic coupling of waves and oscillations in the lower solar atmosphere: can the tail wag the dog?

2005 ◽  
Vol 364 (1839) ◽  
pp. 351-381 ◽  
Author(s):  
Robert Erdélyi
Keyword(s):  
Magnetic Fields ◽  
Solar Atmosphere ◽  
Acoustic Waves ◽  
Large Scale ◽  
Magnetic Coupling ◽  
Small Scale ◽  
Coupling Mechanism ◽  
Frequency Shifts ◽  
Characteristic Features ◽  
Lower Solar Atmosphere

Can the ubiquitously magnetic solar atmosphere have any effect on solar global oscillations? Traditionally, solar atmospheric magnetic fields are considered to be somewhat less important for the existence and characteristic features of solar global oscillations ( p , f and the not-yet-observed g -modes). In this paper, I demonstrate the importance of the presence of magnetism and plasma dynamics for global resonant oscillations in the solar atmosphere. In particular, in the lower part of the solar atmosphere there are both coherent and random components of magnetic fields and velocity fields, each of which contribute on its own to the line widths and frequency variations of solar global acoustic waves. Changes in the coherent large-scale atmospheric magnetic fields cause frequency shifts of global oscillations over a solar cycle. The random character of the continuously emerging, more localized, magnetic carpet (i.e. small-scale, possibly even sub-resolution, loops) gives rise to additional frequency shifts. On the other hand, random and organized surface and sub-surface flows, like surface granulation, meridional flows or differential rotation, also affect the coupling mechanism of global oscillations to the lower magnetic atmosphere. The competition between magnetic fields and flows is inevitable. Finally, I shall discuss how solar global oscillations can resonantly interact with the overlaying inhomogeneous lower solar atmosphere embedded in a magnetic carpet. Line width broadening and distorsion of global acoustic modes will be discussed. The latter is suggested to be tested and measured by using ring-analysis techniques.

Nonlinear magneto-acoustic waves in the solar atmosphere

2001 ◽  
Vol 34 (2-4) ◽  
pp. 399-409
Author(s):  
César A. Mendoza-Briceño ◽  
Miguel H. Ibáñez ◽  
Valery M. Nakariakov
Keyword(s):  
Solar Atmosphere ◽  
Acoustic Waves

On the observation of traveling acoustic waves in the solar atmosphere using a magneto-optical filter

2007 ◽  
Vol 328 (3-4) ◽  
pp. 211-214 ◽  
Author(s):  
M. Haberreiter ◽  
W. Finsterle ◽  
S. M. Jefferies
Keyword(s):  
Solar Atmosphere ◽  
Acoustic Waves ◽  
Optical Filter

Dynamics and Heating of Chromospheres

2004 ◽  
Vol 219 ◽  
pp. 115-122 ◽  
Author(s):  
Wolfgang Kalkofen
Keyword(s):  
Temperature Profile ◽  
Acoustic Waves ◽  
Large Amplitude ◽  
Time Dependent ◽  
Temperature Structure ◽  
The Sun ◽  
Late Type ◽  
Spherical Waves ◽  
Spatial And Temporal Characteristics ◽  
Chromospheric Heating

Heating and dynamics of the solar as well as stellar chromospheres are separate phenomena, judging by their spatial and temporal characteristics in the Sun. Simulations of chromospheric heating in late-type stars as well as simulations of the dynamics of the large-amplitude oscillations of internetwork calcium bright points in the solar atmosphere reproduce the main features of the respective phenomena. Differences between models and observations imply (1) that the Sun has a permanent, hot chromosphere and that its temperature structure cannot be obtained by averaging the time-dependent temperature profile of a model that describes only the oscillations, and (2) that the acoustic waves causing the dynamics and the heating propagate upward as spherical waves.

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