2025 Articles

Measurements of the Perpendicular Correlation Length of Coronal Alfvénic Waves with DKIST

Hahn, Michael; Hofmeister, Stefan J.; Koukras, Alexandros; Savin, Daniel Wolf

We have measured the perpendicular correlation length L⊥ of Alfvénic waves in the corona using data from the Daniel K. Inouye Solar Telescope (DKIST) Cryogenic Near Infrared Spectropolarimeter (Cryo-NIRSP) instrument. These data have high spatial resolution and were collected using a raster, enabling us to unambiguously identify the parallel and perpendicular directions with respect to the wave propagation. We find that the measured median L⊥ ≈ 3.5 Mm, which is about half the value found by previous measurements. We ascribe the smaller value measured here to the improved spatial resolution of DKIST. There is a gradual decrease of L⊥ as a function of frequency. We also computed the spatial correlation length of the observed static density structures and found that their typical correlation lengths of ≈8.4 Mm were significantly larger than those of the waves.