Statistical investigation of decayless oscillations in small-scale coronal loops observed by Solar Orbiter/EUI^⋆

¹ Aryabhatta Research Institute of Observational Sciences, Nainital 263002, India
e-mail: vaibhavpant55@gmail.com
² Indian Institute of Astrophysics, Bangalore 560034, India
³ Joint Astronomy Programme and Department of Physics, Indian Institute of Science, Bangalore 560012, India
⁴ Solar-Terrestrial Centre of Excellence – SIDC, Royal Observatory of Belgium, Ringlaan 3 Av. Circulaire, 1180 Brussels, Belgium
⁵ Skobeltsyn Institute of Nuclear Physics, Moscow State University, 119991 Moscow, Russia
⁶ Centre for mathematical Plasma Astrophysics, Mathematics Department, KU Leuven, Celestijnenlaan 200B bus 2400, 3001 Leuven, Belgium
⁷ Center of Excellence in Space Science, IISER Kolkata, Kolkata 700064, India

Received: 17 April 2023
Accepted: 19 December 2023

Abstract

Decayless kink oscillations are omnipresent in the solar atmosphere, and they are a viable candidate for coronal heating. Although there have been extensive studies of decayless oscillations in coronal loops with lengths of a few hundred megameters, the properties of these oscillations in small-scale (∼10 mm) loops are yet to be explored. In this study, we present the properties of decayless oscillations in small loops embedded in the quiet corona and coronal holes. We use high-resolution observations from the Extreme Ultraviolet Imager on board Solar Orbiter with pixel scales of 210 km and a cadence of 5 s or better. We analysed 42 oscillations in coronal loops with loop lengths varying between 3 to 23 mm. The average displacement amplitude is found to be 134 km. The oscillations period has a range of 28 to 272 s, and the velocity amplitudes range from 2.1 to 16.4 km s⁻¹. The variation in the loop length with the period does not indicate a significant correlation. The wave mode of these waves is uncertain, and standing waves are one possibility. Our results for the coronal seismology and energy flux estimates were obtained considering standing modes. The observed kink speeds are lower than those observed in active region coronal loops. We obtain an average magnetic field value of 2.1 G. We estimated the energy flux with a broad range of 0.6–313 W m⁻². Moreover, we note that short-period decayless oscillations are not prevalent in the quiet Sun and coronal holes. Our study suggests that decayless oscillations in small-scale coronal loops are unlikely to provide enough energy to heat the quiet Sun and accelerate solar wind in coronal holes.