The Effect of the Chromospheric Temperature on Coronal Heating

Abstract

Recent observational and numerical studies show a variety of thermal structures in the solar chromosphere. Given that the thermal interplay across the transition region is a key to coronal heating, it is worth investigating how different thermal structures of the chromosphere yield different coronal properties. In this work, by MHD simulations of Alfvén-wave heating of coronal loops, we study how the coronal properties are affected by the chromospheric temperature. To this end, instead of solving the radiative transfer equation, we employ a simple radiative loss function so that the chromospheric temperature is easily tuned. When the chromosphere is hotter, because the chromosphere extends to a larger height, the coronal part of the magnetic loop becomes shorter, which enhances the conductive cooling. A larger loop length is therefore required to maintain the high-temperature corona against the thermal conduction. From our numerical simulations we derive a condition for the coronal formation with respect to the half loop length $l_{\mathrm{loop}}$ in a simple form: $l_{\mathrm{loop}}>a{T}_{\min }+l_{\mathrm{th}}$, where $T_{\min }$ is the minimum temperature in the atmosphere and parameters $a$ and $l_{\mathrm{th}}$ have negative dependencies on the coronal field strength. Our conclusion is that the chromospheric temperature has a non-negligible impact on coronal heating for loops with small length and weak coronal field. In particular, the enhanced chromospheric heating could prevent the formation of the corona.

18 pages, 19 figures, accepted for publication in ApJ

References in corpus (10)

• Self-consistent Coronal Heating and Solar Wind Acceleration from Anisotropic Magnetohydrodynamic Turbulence
• A giant comet-like cloud of hydrogen escaping the warm Neptune-mass exoplanet GJ 436b
• Prevalence of Small-scale Jets from the Networks of the Solar Transition Region and Chromosphere
• On the prevalence of small-scale twist in the solar chromosphere and transition region
• Three-dimensional simulation of the fast solar wind driven by compressible magnetohydrodynamic turbulence
• Two-dimensional Radiative Magnetohydrodynamic Simulations of Partial Ionization in the Chromosphere. II. Dynamics and Energetics of the Low Solar Atmosphere
• Mapping Solar Magnetic Fields from the Photosphere to the Base of the Corona
• Direct and Inverse Cascades in the Acceleration Region of the Fast Solar Wind
• Stellar coronal X-ray emission and surface magnetic flux
• Solar slow magneto-acoustic-gravity waves: an erratum correction and a revisited scenario

Cited by in corpus (1)

• Assessing the capability of a model-based stellar XUV estimation