Mysteries of the solar chromosphere explored using the high-resolution observations

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• Juie Shetye (University of Warwick)
• Monday 05 February 2018, 14:00-15:00
• MR14, Centre for Mathematical Sciences, Wilberforce Road, Cambridge.

If you have a question about this talk, please contact Dr. Yufeng Lin.

The solar chromosphere serves as a bridging layer between the photosphere and the corona and is often neglected. This dynamic layer is filled with a plethora of features that vary at small time and space scales. With the advent of new and improved methods of observations we are not only able to unveil new features but also understand the physical properties of others. Here I present a statistical study of spicules obtained from spectral images, taken from the CRISP instrument at the Swedish 1-m Solar Telescope in H-alpha 656.28 nm wavelength. Remarkably, many of these fast spicules display apparent unphysical velocities above 5000 km/s, very short lifetimes of up to 20 s combined with width or thickness of 100 km and apparent lengths of around 3500 km. We interpret the observations as mass motions (of flux tubes, maybe sheets) that appear in the field-of-view of CRISP ’s 0.0060 nm filters in the line of sight, along with their projection as we scan. Furthermore, such spicules exhibited transverse motion associated with these structures, which in some cases could be related to high-frequency magneto-hydrodynamic (MHD) kink-waves. Can these high-frequency waves be transferred to the solar corona and contribute to coronal heating? MHD waves are not only responsible for the generation and evolution of these events but also are responsible for energy and mass transport. At present, MHD LareXd simulations to be carried at CFSA , hope to provide some insight into the dynamics of such events. Are spicules the only events in the chromosphere? I will show dynamic events that swirl and can further explain aspects of chromospheric dynamics never understood before.

Observations of small-scale events in the chromosphere further highlight the need to understand the plasma environment associated with the events. We still don’t know where the Hydrogen lines are formed, or if a feature observed in the Calcium line, occurs at the corona or the chromosphere. This raises the need to develop a thorough radiative transfer code (e.g expansion of CHIANTI ) for the chromosphere. In addition, the current work presented already tests the limits of current telescopes in terms of the temporal and spatial resolution. The answer to exploring the depth of chromosphere lies in building next-generation solar physics observatories such as DKIST that have 3 times more spatial resolution than CRISP and much higher temporal resolution.

This talk is part of the DAMTP Astrophysics Seminars series.

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