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 loop in a simple form: ${l}_{\mathrm{loop}}\gt {{aT}}_{\min }+{l}_{\mathrm{th}}$ , where ${T}_{\min }$ is the minimum temperature in the atmosphere, and parameters a and l th have negative dependencies on the coronal field strength. Our conclusion is that the chromospheric temperature has a nonnegligible impact on coronal heating for loops with small lengths and weak coronal fields. In particular, the enhanced chromospheric heating could prevent the formation of the corona.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- October 2022
- DOI:
- 10.3847/1538-4357/ac91c8
- arXiv:
- arXiv:2209.10156
- Bibcode:
- 2022ApJ...938..126W
- Keywords:
-
- Solar corona;
- Magnetohydrodynamical simulations;
- Solar coronal loops;
- 1483;
- 1966;
- 1485;
- Astrophysics - Solar and Stellar Astrophysics
- E-Print:
- 18 pages, 19 figures, accepted for publication in ApJ