Decayless oscillations in solar coronal bright points

Abstract

Decayless kink oscillations of solar coronal loops (or decayless oscillations for short) have attracted great attention since their discovery. Coronal bright points (CBPs) are mini-active regions and consist of loops with a small size. However, decayless oscillations in CBPs have not been widely reported. In this study, we identified this kind of oscillations in some CBPs using 171 Å\, images taken by the Atmospheric Imaging Assembly (AIA) onboard the Solar Dynamics Observatory (SDO). After using the motion magnification algorithm to increase oscillation amplitudes, we made time-distance maps to identify the oscillatory signals. We also estimated the loop lengths and velocity amplitudes. We analysed 23 CBPs, and found 31 oscillation events in 16 of them. The oscillation periods range from 1 to 8 minutes (on average about 5 minutes), and the displacement amplitudes have an average value of 0.07 Mm. The average loop length and velocity amplitude are 23 Mm and 1.57 \kms, respectively. Relationships between different oscillation paraments are also examined. Additionally, we performed a simple forward model to illustrate how these sub-pixel oscillation amplitudes (less than 0.4 Mm) could be detected. Results of the model confirm the reliability of our data processing methods. Our study shows for the first time that decayless oscillations are common in small-scale loops of CBPs. These oscillations allow for seismological diagnostics of the Alfvén speed and magnetic field strength in the corona.

19 pages, 7 figures. Accepted for publication in The Astrophysical Journal

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• Two-Spacecraft Detection of Short-period Decayless Kink Oscillations of Solar Coronal Loops
• The Role of High-frequency Transverse Oscillations in Coronal Heating
• 30-min Decayless Kink Oscillations in a Very Long Bundle of Solar Coronal Plasma Loops
• Alfvénic motions arising from asymmetric acoustic wave drivers in solar magnetic structures
• Decayless oscillations in 3D coronal loops excited by a power-law driver
• Do Periods of Decayless Kink Oscillations of Solar Coronal Loops Depend on Noise?
• Propagating Kink Waves in an Open Coronal Magnetic Flux Tube with Gravitational Stratification: Magnetohydrodynamic Simulation and Forward Modelling
• Characteristics and Energy Flux Distributions of Decayless Transverse Oscillations Depending on Coronal Regions
• Kelvin-Helmholtz instability and heating in oscillating loops perturbed by power-law transverse wave drivers
• Automated analysis of oscillations in coronal bright points
• High-Frequency Magnetohydrodynamic Waves with Substantial Energy in the Solar Polar Corona
• Spectra of standing kink waves in loops and the effects of the lower solar atmosphere