Running waves observed by Hinode

Liang, Hong-Fei; Yang, Wenbo; Yang, Rujuan

doi:10.1016/j.newast.2011.06.006

Cited by 4 publications

(2 citation statements)

References 18 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The PDs propagate outward (e.g. in AIA 171) in the circular or arc shape, similar to those observed in the chromosphere (Liang et al 2011(Liang et al , 2012. In contrast, the PDs in non-sunspot coronal loops appear to be different in some features.…”

Section: Observational Motivationsupporting

confidence: 62%

Three-Dimensional Magnetohydrodynamic Modeling of Propagating Disturbances in Fan-Like Coronal Loops

Wang

Ofman

Davila

2013

ApJ

View full text Add to dashboard Cite

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.

show abstract

Section: Observational Motivationsupporting

confidence: 62%

Three-Dimensional Magnetohydrodynamic Modeling of Propagating Disturbances in Fan-Like Coronal Loops

Wang

Ofman

Davila

2013

ApJ

View full text Add to dashboard Cite

show abstract

“…However, it is extremely difficult to select an adaptive intensity threshold and/or gradient to objectively define the shape of UFs due to their low contrast and low luminance. Therefore, the technique of running difference is usually selected (Brisken & Zirin 1997;Rouppe van der Voort et al 2003;Nagashima et al 2007;Socas-Navarro et al 2009;Liang et al 2011Liang et al , 2012 to highlight UFs. A running difference image is the difference between every image in the time sequence compared with the previous image.…”

Section: Introductionmentioning

confidence: 99%

Identification of emission sources of umbral flashes using phase congruency

Feng¹,

Yu²,

Yang³

et al. 2014

Res. Astron. Astrophys.

View full text Add to dashboard Cite

The emission sources of umbral flashes (UFs) are believed to be closely related to running umbral and penumbral waves, and are concluded to be associated with umbral dots in the solar photosphere. Accurate identification of emission sources of UFs is crucial for investigating these physical phenomena and their inherent relationships. A relatively novel model of shape perception, namely phase congruency (PC), uses phase information in the Fourier domain to identify the geometrical shape of the region of interest in different intensity levels, rather than intensity or gradient. Previous studies indicate that the model is suitable for identifying features with low contrast and low luminance. In the present paper, we applied the PC model to identify the emission sources of UFs and to locate their positions. For illustrating the high performance of our proposed method, two time sequences of Ca II H images derived from the Hinode/SOT on 2010 August 10 and 2013 August 20 were used. Furthermore, we also compared these results with the analysis results that are identified by the traditional/classical identification methods, including the gray-scale adjusted technique and the running difference technique. The result of our analysis demonstrates that our proposed method is more accurate and effective than the traditional identification methods when applied to identifying the emission sources of UFs and to locating their positions.

show abstract

Waves in Solar Coronal Loops

Wang

2016

Low‐Frequency Waves in Space Plasmas

View full text Add to dashboard Cite

Recent observations have revealed the ubiquitous presence of magnetohydrodynamic (MHD) waves and oscillations in the solar corona. The aim of this review is to present recent progress in the observational study of four types of wave (or oscillation) phenomena mainly occurring in active region coronal loops, including (i) flare-induced slow mode oscillations, (ii) fast kink mode oscillations, (iii) propa-gating slow magnetoacoustic waves, and (iv) ubiquitous propagating kink (Alfvenic) waves. This review not only comprehensively outlines various aspects of these waves and coronal seismology, but also highlights the topics that are newly emerging or hotly debated, thus can provide readers a useful guidance on further studies of their interested topics.

show abstract

Running waves observed by Hinode

Cited by 4 publications

References 18 publications

Three-Dimensional Magnetohydrodynamic Modeling of Propagating Disturbances in Fan-Like Coronal Loops

Three-Dimensional Magnetohydrodynamic Modeling of Propagating Disturbances in Fan-Like Coronal Loops

Identification of emission sources of umbral flashes using phase congruency

Waves in Solar Coronal Loops

Contact Info

Product

Resources

About