SLOW MAGNETOSONIC WAVES AND FAST FLOWS IN ACTIVE REGION LOOPS

Journal Article · Wed Aug 01 00:00:00 EDT 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/754/2/111· OSTI ID:22039232

Ofman, L; Wang, T J ^[1]; Davila, J M ^[2]

---

1. Department of Physics, Catholic University of America, Washington, DC 20064 (United States)
2. NASA Goddard Space Flight Center, Code 671, Greenbelt, MD 20771 (United States)

Recent extreme ultraviolet spectroscopic observations indicate that slow magnetosonic waves are present in active region (AR) loops. Some of the spectral data were also interpreted as evidence of fast ({approx}100-300 km s{sup -1}) quasi-periodic flows. We have performed three-dimensional magnetohydrodynamic (3D MHD) modeling of a bipolar AR that contains impulsively generated waves and flows in coronal loops. The model AR is initiated with a dipole magnetic field and gravitationally stratified density, with an upflow-driven steadily or periodically in localized regions at the footpoints of magnetic loops. The resulting flows along the magnetic field lines of the AR produce higher density loops compared to the surrounding plasma by injection of material into the flux tubes and the establishment of siphon flow. We find that the impulsive onset of flows with subsonic speeds result in the excitation of damped slow magnetosonic waves that propagate along the loops and coupled nonlinearly driven fast-mode waves. The phase speed of the slow magnetosonic waves is close to the coronal sound speed. When the amplitude of the driving pulses is increased we find that slow shock-like wave trains are produced. When the upflows are driven periodically, undamped oscillations are produced with periods determined by the periodicity of the upflows. Based on the results of the 3D MHD model we suggest that the observed slow magnetosonic waves and persistent upflows may be produced by the same impulsive events at the bases of ARs.

• OSTI ID: 22039232
• Journal Information: Astrophysical Journal, Vol. 754, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ASTRONOMY
ASTROPHYSICS
COMPUTERIZED SIMULATION
EXCITATION
EXTREME ULTRAVIOLET RADIATION
EXTREME ULTRAVIOLET SPECTRA
MAGNETIC FIELDS
MAGNETOACOUSTIC WAVES
MAGNETOHYDRODYNAMICS
OSCILLATIONS
PERIODICITY
PLASMA
SOLAR CORONA
SOUND WAVES
SUN
THREE-DIMENSIONAL CALCULATIONS