Three-Dimensional MHD Models of Waves and Flows in Coronal Active Region Loops

Details Three-Dimensional MHD Models of Waves and Flows in Coronal Active Region Loops Three-Dimensional MHD Models of Waves and Flows in Coronal Active Region Loops

Dec 2011

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011agufmsh34b..02o&link_type=abstract

American Geophysical Union, Fall Meeting 2011, abstract #SH34B-02

Physics

Plasma Physics

[7509] Solar Physics, Astrophysics, And Astronomy / Corona, [7519] Solar Physics, Astrophysics, And Astronomy / Flares, [7836] Space Plasma Physics / Mhd Waves And Instabilities

Scientific paper

Recent observations show that slow magnetosonic waves are present in active region loops, and are often associated with subsonic up-flows of coronal material. In order to study the relation between up-flows and waves we develop a 3D MHD model of an idealized bi-polar active region with flows in coronal loops. The model is initiated with a dipole magnetic field and gravitationally stratified isothermal atmosphere. To model the effects of flares, coronal material is injected in small-scale regions at the base of the model active region. The up-flows have sub-sonic speeds of ˜100 km/s and are steady or periodic, producing higher density loops by filling magnetic flux-tubes with injected material. We find that the up-flows produce fast and slow magnetosonic waves that propagate in the coronal loops. We perform a parametric study of up-flow magnitude and periodicity, and the relation with the resulting waves. As expected, we find that the up-flow speed decreases with loop height due to the diverge of the flux tubes, while the slow magnetosonic speed is independent of height. When the amplitude of the driving pulses is increased above the sound speed, we find that slow shocks are produced in the loops. Using the results of the 3D MHD model we show that observed slow magnetosonic waves in active region loops can be driven by impulsive flare-produced up-flows at the transition region/corona interface of active regions.

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