Peculiarities of entropy and magnetosonic waves in optically thin cosmic plasma |
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Authors: | B. V. Somov N. S. Dzhalilov J. Staude |
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Affiliation: | (1) Sternberg Astronomical Institute, Universitetskii pr. 13, Moscow, 119992, Russia;(2) Pushkov Institute of Terrestrial Magnetism, Ionosphere, and Radiowave Propagation, Russian Academy of Sciences, Troitsk, Moscow oblast, 142190, Russia;(3) Shemakha Astrophysical Observatory, National Academy of Sciences of Azerbaijan, Shemakha, 373243, Azerbaijan;(4) An der Sternwarte, Astrophysikalisches Institut Potsdam, Potsdam, 14482, Germany |
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Abstract: | The stability problem for small magnetohydrodynamic (MHD) perturbations in an optically thin, perfectly conducting uniform plasma with a cosmic abundance of elements is solved in the linear approximation. The electron heat conduction along the magnetic field and the proton heat conduction across the field are taken into account. We have shown for the first time that the entropy waves can grow exponentially, while the magnetosonic waves are damped in a wide range of physical conditions closest to the conditions in stellar coronae with the proper allowance for radiative losses. Slow magnetosonic waves are damped particularly rapidly. For the solar corona, the calculated damping decrement of slow magnetosonic waves agrees well with the averaged one in 11 quasi-periodic events observed from the TRACE satellite in extreme ultraviolet radiation. Other possible astrophysical applications of the results obtained are briefly discussed. |
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Keywords: | plasma astrophysics hydrodynamics and shock waves solar coronae flares MHD waves stability magnetic reconnection |
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