Δημοσιεύσεις

Project Acronym: PAS4
Title: Parametric Astrophysical Simulations 4
Affiliation: university of athens
Pi: Kanaris Tsiganos
Research Field: solar physics

A Cancellation Nanoflare Model for Solar Chromospheric and Coronal Heating
by P. Syntelis, E. R. Priest and L. P. Chitta
Abstract:
Recent observations at high spatial resolution have shown that magnetic flux cancellation occurs on the solar surface much more frequently than previously thought, and so this led Priest et al. (2018) to propose magnetic reconnection driven by photospheric flux cancellation as a mechanism for chromospheric and coronal heating. In particular, they estimated analytically the amount of energy released as heat and the height of the energy release during flux cancellation. In the present work, we take the next step in the theory by setting up a two-dimensional resistive MHD simulation of two canceling polarities in the presence of a horizontal external field and a stratified atmosphere in order to check and improve upon the analytical estimates. Computational evaluation of the energy release during reconnection is found to be in good qualitative agreement with the analytical estimates. In addition, we go further and undertake an initial study of the atmospheric response to reconnection. We find that, during the cancellation, either hot ejections or cool ones or a combination of both hot and cool ejections can be formed, depending on the height of the reconnection location. The hot structures can have the density and temperature of coronal loops, while the cooler structures are suggestive of surges and large spicules.
Reference:
A Cancellation Nanoflare Model for Solar Chromospheric and Coronal Heating (P. Syntelis, E. R. Priest and L. P. Chitta), In The Astrophysical Journal, American Astronomical Society, volume 862, 2018.
Bibtex Entry:
@article{priest2018cancellation,
 title = {A Cancellation Nanoflare Model for Solar Chromospheric and Coronal Heating},
 author = {P. Syntelis and E. R. Priest and L. P. Chitta},
 volume = {862},
 number = {2},
 pages = {L24},
 year = {2018},
 bibyear = {2018},
 journal = {The Astrophysical Journal},
 publisher = {American Astronomical Society},
 url = {https://doi.org/10.3847/1538-4357/aafaf8},
 doi = {10.3847/1538-4357/aafaf8},
 abstract = {Recent observations at high spatial resolution have shown that magnetic flux cancellation occurs on the solar surface much more frequently than previously thought, and so this led Priest et al. (2018) to propose magnetic reconnection driven by photospheric flux cancellation as a mechanism for chromospheric and coronal heating. In particular, they estimated analytically the amount of energy released as heat and the height of the energy release during flux cancellation. In the present work, we take the next step in the theory by setting up a two-dimensional resistive MHD simulation of two canceling polarities in the presence of a horizontal external field and a stratified atmosphere in order to check and improve upon the analytical estimates. Computational evaluation of the energy release during reconnection is found to be in good qualitative agreement with the analytical estimates. In addition, we go further and undertake an initial study of the atmospheric response to reconnection. We find that, during the cancellation, either hot ejections or cool ones or a combination of both hot and cool ejections can be formed, depending on the height of the reconnection location. The hot structures can have the density and temperature of coronal loops, while the cooler structures are suggestive of surges and large spicules.},
}