Novel Measurements of Waves and Turbulence in the Corona using High Resolution DKIST Observations

The solar corona is the Sun’s outer atmosphere, with temperatures of millions of degrees. Coronal heating theories aim to explain the high temperature of the corona. Wave-driven models of coronal heating posit that energy is transported to the corona by Alfvenic waves. Although most coronal heating models rely on turbulence, it is not known where and how Alfvenic turbulence emerges in the corona. The project will use the U.S. National Science Foundation Daniel K. Inouye Solar Telescope (Inouye) to conduct novel high spatial, temporal, and spectral resolution observations of the waves, turbulence, and heating in the Sun’s corona. By examining how the power spectrum evolves with height in long streamers and in short loops, the measurements will provide critical constraints for wave-driven models of coronal heating. The project will train a post-doctoral research scientist in solar physics and plasma physics. Most coronal heating theories invoke turbulence to transfer Alfven wave power from initially large length scales to small scales. Turbulence is thought to be driven by nonlinear interactions between counter-propagating Alfven waves. The project proposes to look for signatures of turbulence in the quiet Sun corona up to 1.5 solar radii. Using Inouye, the power spectrum of Alfvenic fluctuations in the corona can be measured up to high frequencies of about 500 mHz which is critical for detecting the early signs of turbulence in the low corona. Preferential ion heating due to wave particle interactions is hypothesized to begin close to the Sun. The project will identify where ions in the quiet corona are heated and test whether the velocity distribution of the ions differs from a Maxwellian distribution. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.