2025/01/07 by R. J. Morton, Momchil Molnar, Morton, Richard J. +5 · 3 citations
Physics and Astronomy · #FOS: Physical sciences #Solar and Space Plasma Dynamics #Solar and Stellar Astrophysics (astro-ph.SR)
paper · pdf · doi:10.48550/arxiv.2501.03758
openalex publication_date 2025/01/07 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
The presence and nature of low-frequency (0.1-10~mHz) Alfvénic waves in the corona has been established over the last decade, with many of these results coming from coronagraphic observations of the infrared Fe XIII line. The Cryo-NIRSP instrument situated at DKIST has recently begun acquiring science quality data of the same Fe XIII line, with at least a factor of 9 improvement in spatial resolution, a factor 30 increase in temporal resolution and an increase in signal-to-noise, when compared to the majority of previously available data. Here we present an analysis of 1~s cadence sit-and-stare data from Cryo-NIRSP, examining the Doppler velocity fluctuations associated with the Fe XIII 1074~nm coronal line. We are able to confirm previous results of Alfvénic waves in the corona as well as explore a new frequency regime. The data reveals that the power law behaviour of the Doppler velocity power spectrum extends to higher frequencies. This result appears to challenge some models of photospheric-driven Alfvénic waves that predict a lack of high frequency wave power in the corona due to strong chromospheric damping. Moreover, the high-frequency waves do not transport as much energy as their low-frequency counterparts, with less time-averaged energy per frequency interval. We are also able to confirm the incompressible nature of the fluctuations with little coherence between the line amplitude and Doppler velocity time-series.