2008/02/24 by S. S. Hasan, A. A. van Ballegooijen · 93 citations
Physics and Astronomy · #Acoustic wave #Chromosphere #Flux (metallurgy) #Flux tube #Ionosphere and magnetosphere dynamics #Magnetic field #Magnetic flux #Magnetohydrodynamic drive #Magnetohydrodynamics #Shock wave #Solar and Space Plasma Dynamics #Stellar, planetary, and galactic studies #Transverse wave #astro-ph
paper · pdf · doi:10.1086/587773
published in The Astrophysical Journal 680(2), 1542-1552 (IOP Publishing) · 30 pages, 8 figures, Accepted in Astrophysical Journal
arxiv created 2008/02/24 · openalex publication_date 2008/06/13 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
We consider recent observations of the chromospheric network and argue that the bright network grains observed in the Ca II H and K lines are heated by an as-yet-unidentified quasi-steady process. We propose that the heating is caused by dissipation of short-period magnetoacoustic waves in magnetic flux tubes (periods less than 100 s). Magnetohydrodynamic (MHD) models of such waves are presented. We consider wave generation in the network due to two separate processes: (1) transverse motions at the base of the flux tube and (2) the absorption of acoustic waves generated in the ambient medium. We find that the former mechanism leads to efficient heating of the chromosphere by slow magnetoacoustic waves propagating along magnetic field lines. This heating is produced by shock waves with a horizontal size of a few hundred kilometers. In contrast, acoustic waves excited in the ambient medium are converted into transverse fast modes that travel rapidly through the flux tube and do not form shocks, unless the acoustic sources are located within 100 km from the tube axis. We conclude that the magnetic network may be heated by magnetoacoustic waves that are generated in or near the flux tubes.