[Loops] new loop paper of your interest

[Tongjiang Wang]

Hi Everyone

I have a new paper just published which may be of your interest:

Effect of Transport Coefficients on Excitation of Flare-induced Standing 
Slow-mode Waves in Coronal Loops

https://doi.org/10.3847/1538-4357/aac38a

Abstract
Standing slow-mode waves have been recently observed in flaring loops by 
the Atmospheric Imaging Assembly of the Solar Dynamics Observatory. By 
means of the coronal seismology technique, transport coefficients in hot 
(~10 MK) plasma were determined by Wang et al., revealing that thermal 
conductivity is nearly suppressed and compressive viscosity is enhanced by 
more than an order of magnitude. In this study, we use 1D nonlinear MHD 
simulations to validate the predicted results from the linear theory and 
investigate the standing slow-mode wave excitation mechanism. We first 
explore the wave trigger based on the magnetic field extrapolation and 
flare emission features. Using a flow pulse driven at one footpoint, we 
simulate the wave excitation in two types of loop models: Model 1 with the 
classical transport coefficients and Model 2 with the 
seismology-determined transport coefficients. We find that Model 2 can 
form the standing wave pattern (within about one period) from initial 
propagating disturbances much faster than Model 1, in better agreement 
with the observations. Simulations of the harmonic waves and the Fourier 
decomposition analysis show that the scaling law between damping time (Td) 
and wave period (P) follows Td ~ P^2 in Model 2, while Td ~ P in Model 1. 
This indicates that the largely enhanced viscosity efficiently increases 
the dissipation of higher harmonic components, favoring the quick 
formation of the fundamental standing mode. Our study suggests that 
observational constraints on the transport coefficients are important in 
understanding both the wave excitation and damping mechanisms.

Thank you

Best Regards

Tongjiang


-------------------
Tongjiang Wang

NASA GSFC - Code 671
Bldg 21 - RM 022
Greenbelt, MD 20771

Tel. 301-286-4168
tongjiang.wang at nasa.gov