GENERATION OF DYNAMO MAGNETIC-FIELDS IN THE PRIMORDIAL SOLAR NEBULA

We study the problem of the existence of dynamo-generated magnetic fields in the primordial solar nebula. The combined action of Keplerian rotation and helical convection enables an αω dynamo to generate large-scale magnetic fields in parts of the nebula where levels of electrical conductivity are high enough to provide coupling between the gas and the magnetic field. The aim of this paper is to identify those regions of the nebula where an αω dynamo is able to maintain a magnetic field for a relatively long period of time. We calculate the electrical conductivity of nebular gas and subsequently the radial distribution of the local dynamo number for two specific nebular models-a viscous accretion disk model, and the quiescent minimum mass nebula. Our calculations show that magnetic fields can be easily generated and maintained by an αω dynamo in the inner and outer parts of the nebula; however, in the middle region of the nebula, between, say, 2 and 5 AU, the existence of dynamo-generated fields is questionable. © 1992.