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We investigate the decayless regime of coronal kink oscillations recentlydiscovered in the Solar Dynamics Observatory (SDO)/AIA data. In contrast todecaying kink oscillations that are excited by impulsive dynamical processes,this type of transverse oscillations is not connected to any external impulsiveimpact, such as a flare or CME, and does not show any significant decay.Moreover the amplitude of these decayless oscillations is typically lower thanthat of decaying oscillations. The aim of this research is to estimate theprevalence of this phenomenon and its characteristic signatures. We analysed 21active regions (NOAA 11637--11657) observed in January 2013 in the 171 Achannel of SDO/AIA. For each active region we inspected six hours ofobservations, constructing time-distance plots for the slits positioned acrosspronounced bright loops. The oscillatory patterns in time-distance plots werevisually identified and the oscillation periods and amplitudes were measured.We also estimated the length of each oscillating loop. Low-amplitude decaylesskink oscillations are found to be present in the majority of the analysedactive regions. The oscillation periods lie in the range from 1.5 to10~minutes. In two active regions with insufficient observation conditions wedid not identify any oscillation patterns. The oscillation periods are found toincrease with the length of the oscillating loop. The considered type ofcoronal oscillations is a common phenomenon in the corona. The establisheddependence of the oscillation period on the loop length is consistent withtheir interpretation in terms of standing kink waves.

Decayless low-amplitude kink oscillations: a common phenomenon in the solar corona?