THREE-DIMENSIONAL MAGNETOHYDRODYNAMIC MODELING OF PROPAGATING DISTURBANCES IN FAN-LIKE CORONAL LOOPS

Journal Article · Fri Sep 20 04:00:00 EDT 2013 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/775/1/L23· OSTI ID:22215437

Wang, Tongjiang; Ofman, Leon ^[1]

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1. Department of Physics, Catholic University of America, 620 Michigan Avenue NE, Washington, DC 20064 (United States)

Quasi-periodic propagating intensity disturbances (PDs) have been observed in large coronal loops in EUV images over a decade, and are widely accepted to be slow magnetosonic waves. However, spectroscopic observations from Hinode/EIS revealed their association with persistent coronal upflows, making this interpretation debatable. Motivated by the scenario that the coronal upflows could be the cumulative result of numerous individual flow pulses generated by sporadic heating events (nanoflares) at the loop base, we construct a velocity driver with repetitive tiny pulses, whose energy frequency distribution follows the flare power-law scaling. We then perform three-dimensional MHD modeling of an idealized bipolar active region by applying this broadband velocity driver at the footpoints of large coronal loops which appear open in the computational domain. Our model successfully reproduces the PDs with similar features as the observed, and shows that any upflow pulses inevitably excite slow magnetosonic wave disturbances propagating along the loop. We find that the generated PDs are dominated by the wave signature as their propagation speeds are consistent with the wave speed in the presence of flows, and the injected flows rapidly decelerate with height. Our simulation results suggest that the observed PDs and associated persistent upflows may be produced by small-scale impulsive heating events (nanoflares) at the loop base in the corona, and that the flows and waves may both contribute to the PDs at lower heights.

• OSTI ID: 22215437
• Journal Information: Astrophysical Journal Letters, Journal Name: Astrophysical Journal Letters Journal Issue: 1 Vol. 775; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
BLOWERS
DISTURBANCES
HEATING
HEIGHT
MAGNETOACOUSTIC WAVES
MAGNETOHYDRODYNAMICS
OSCILLATIONS
PERIODICITY
PULSES
SIMULATION
SUN
THREE-DIMENSIONAL CALCULATIONS
ULTRAVIOLET RADIATION
VELOCITY