Analysis of oscillations and kinematics of coronal rain observed by IRIS and Hinode/SOT
Solar Physics in the era of ultra-high spatial resolution: Getting ready for DKIST
Petra Kohutova
Erwin Verwichte (University of Warwick)
University of Warwick
Coronal rain composed of cool plasma condensations falling from coronal heights along magnetic field lines is a phenomenon occurring in active region coronal loops. It is a result of catastrophic cooling following a thermal instability onset in a coronal loop with footpoint-concentrated heating. Recent high resolution observations have shown that coronal rain is much more common than previously thought, suggesting its important role in the chromosphere-corona mass cycle. Small sizes of plasma blobs make coronal rain a good tracer of the coronal magnetic field thus highlighting its suitability for investigating the fine-scale coronal structure and its helioseismologic potential.
We present the analysis of MHD oscillations and kinematics of the coronal rain observed in chromospheric and transition region lines by IRIS and Hinode/SOT. Two different regimes of transverse oscillations traced by the rain in the studied coronal loop are detected: small-scale persistent oscillations driven by a continuously operating process and localised large-scale oscillations excited by a transient mechanism. The plasma condensations are found to move with speeds ranging from few km/s up to 180 km/s and with accelerations largely below the free fall rate. The broad velocity distribution, sub-ballistic motion and complex velocity profiles of individual rain blobs showing multiple acceleration and deceleration phases suggest that forces other than gravity have significant effect on the evolution of the coronal rain.


09:00 - 10:30