Behaviour of oscillations in loop structures above active regions
arXiv:1505.02857 · doi:10.1016/j.asr.2015.05.015
Abstract
In this study we combine the multiwavelength ultraviolet -- optical (Solar Dynamics Observatory, SDO) and radio (Nobeyama Radioheliograph, NoRH) observations to get further insight into space-frequency distribution of oscillations at different atmospheric levels of the Sun. We processed the observational data on NOAA 11711 active region and found oscillations propagating from the photospheric level through the transition region upward into the corona. The power maps of low-frequency (1--2 mHz) oscillations reproduce well the fan-like coronal structures visible in the Fe ix 171A line. High frequency oscillations (5--7 mHz) propagate along the vertical magnetic field lines and concentrate inside small-scale elements in the umbra and at the umbra-penumbra boundary. We investigated the dependence of the dominant oscillation frequency upon the distance from the sunspot barycentre to estimate inclination of magnetic tubes in higher levels of sunspots where it cannot be measured directly, and found that this angle is close to 40 degrees above the umbra boundaries in the transition region.
References in corpus (14)
- Multiwavelength studies of MHD waves in the solar chromosphere: An overview of recent results
- The Nature of Running Penumbral Waves Revealed
- Observation of multiple sausage oscillations in cool postflare loop
- Sunspot Waves and Triggering of Homologous Active Region Jets
- Small-scale chromospheric jets above a sunspot light bridge
- Oscillating light wall above a sunspot light bridge
- Oscillations in a sunspot with light bridges
- Wave dynamics in a sunspot umbra
- High Resolution Observations of Chromospheric Jets in Sunspot Umbra
- Dynamics in Sunspot Umbra as Seen in New Solar Telescope and Interface Region Imaging Spectrograph Data
- The multifrequency Siberian Radioheliograph
- Sunspot waves and flare energy release
- Lateral downflows in sunspot penumbral filaments and their temporal evolution
- Oscillations Above Sunspots and Faculae: Height Stratification and Relation to Coronal Fan Structure