Chromospheric Magnetic Reconnection and Its Possible Relationship to Coronal Heating

Abstract

Coronal heating is clearly related to the coronal magnetic field. This may be due to a passive role of the magnetic field in modifying wave propagation and dissipation or to an active role resulting from the liberation of magnetic energy by reconnection or in some other way. The purpose of this article is to examine the consequences of reconnection at the chromospheric level rather than in the corona. We note that the chromosphere is indeed a favorable site for reconnection to occur, since the resistivity is greatest in that region - specifically at the temperature-minimum location. Chromospheric reconnection can lead to coronal heating by Joule heating, by the generation and subsequent dissipation of high-frequency Alfvén and magnetacoustic waves, or by the response of the coronal magnetic field to a sudden change in connectivity. The second process could also contribute to heating of the solar wind, since high-frequency Alfvén waves can be absorbed by cyclotron damping. We note also that chromospheric reconnection could inject sufficient chromospheric gas into the corona to balance the known steady downflow of coronal gas through the transition region. It is also possible that chromospheric reconnection plays a role in the first ionization potential effect.