High-frequency wave power observed in the solar chromosphere with IBIS and ALMA

Abstract

We present observational constraints on the chromospheric heating contribution from acoustic waves with frequencies between 5 and 50 mHz. We utilize observations from the Dunn Solar Telescope in New Mexico complemented with observations from the Atacama Large Millimeter Array collected on 2017 April 23. The properties of the power spectra of the various quantities are derived from the spectral lines of Ca II 854.2 nm, H I 656.3 nm, and the millimeter continuum at 1.25 mm and 3 mm. At the observed frequencies the diagnostics almost all show a power law behavior, whose particulars (slope, peak and white noise floors) are correlated with the type of solar feature (internetwork, network, plage). In order to disentangle the vertical versus transverse plasma motions we examine two different fields of view; one near disk center and the other close to the limb. To infer the acoustic flux in the middle chromosphere, we compare our observations with synthetic observables from the timedependent radiative hydrodynamic RADYN code. Our findings show that acoustic waves carry up to about 1 kW m −2 of energy flux in the middle chromosphere, which is not enough to maintain the quiet chromosphere, contrary to previous publications.

The Atmospheric Response to High Nonthermal Electron Beam Fluxes in Solar Flares. II. Hydrogen Broadening Predictions for Solar Flare Observations with the Daniel K. Inouye Solar Telescope

“…"Quiet Sun" synthesis models have started to consider the advantages of these accurate, self-consistent hydrogen broadening profiles as well (Bjørgen et al 2019;Marchenko et al 2021). Here we describe the implementation of new line profile functions in the state-of-the-art RHD code RADYN, which is widely used for simulations of a wide variety of solar flare phenomena (Simões et al 2017;Polito et al 2019;Sadykov et al 2020;Monson et al 2021), Ellerman bombs (Hong et al 2017;Reid et al 2017), nanoflares (Testa et al 2014;Polito et al 2018), and chromospheric dynamics such as spicules and shocks (Carlsson & Stein 2002;Wedemeyer-Böhm & Carlsson 2011;Guerreiro et al 2013;Molnar et al 2021). The updated hydrogen line profile functions are known as the TB09+HM88 profiles, which are extensions of the VCS unified theory calculations to higher-n j lines with self-consistent, non-ideal broadening from electron collisions and proton/ion perturbations.…”