CHROMOSPHERIC HEATING BY ELECTRIC CURRENTS INDUCED BY FLUCTUATING MAGNETIC ELEMENTS

We refer to two papers by Goodman (1995, 1996) on the heating of the c hromosphere by large scale electric currents, and to our paper (Lorrai n and Koutchmy, 1993) on magnetic elements. Goodman assumes that the d ynamo that runs a magnetic element stops operating at t = 0. From then on, the magnetic field decays exponentially, and the induced current; heat the chromosphere. The time constants calculated by Goodman disag ree with the observed values, possibly because he disregards the drivi ng dynamo. Also, he assumes static conditions, but his magnetic force density appears suddenly when the dynamo stops, and it is about equal to the gravitational force density. The magnetic force acts downward a nd fluctuations in the current flowing through the magnetic element sh ould induce vertical oscillations at the photosphere. This point shoul d be investigated further.