paper

Revisiting the relation between nonthermal line widths and transverse MHD wave amplitudes

arXiv:2007.02836 · doi:10.3847/1538-4357/aba429

Abstract

Observations and 3D MHD simulations of the transverse MHD waves in the solar corona have established that true wave energies hide in the nonthermal line widths of the optically thin emission lines. This displays the need for a relation between the nonthermal line widths and transverse wave amplitudes for estimating the true wave energies. In the past decade, several studies have assumed that the root mean square (rms) wave amplitudes are larger than nonthermal line widths by a factor of . However, a few studies have ignored this factor while estimating rms wave amplitudes. Thus there appears to exist a discrepancy in this relation. In this study, we investigate the dependence of nonthermal line widths on wave amplitudes by constructing a simple mathematical model followed by 3D MHD simulations. We derive this relation for the linearly polarised, circularly polarised oscillations, and oscillations excited by multiple velocity drivers. We note a fairly good match between mathematical models and numerical simulations. We conclude that the rms wave amplitudes are never greater than the nonthermal line widths which raises questions about earlier studies claiming transverse waves carry enough energy to heat the solar corona.

17 pages and 5 figures. Accepted for the publication in The Astrophysical Journal. (Few typos are corrected in this version)

References in corpus (10)

Revisiting the relation between nonthermal line widths and transverse MHD wave amplitudes · wovepaper