Planetesimal Aggregation Driven by Impulse Magnetic Fields in Protoplanetary Nebulae
Authors:
          I. Tunyi, Geophysical Institute of the Slovak Academy of Sciences, Bratislava, Slovak Republic
          P. Guba, Geophysical Institute of the Slovak Academy of Sciences, Bratislava, Slovak Republic
          L. E. Roth, Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
          M. Timko, Institute of Experimental Physics of the Slovak Academy of Sciences, Kosice, Slovak Republic

Abstract:
          The lightning discharge generated in the protoplanetary nebula is treated as a temporally isolated surge in the flow of electrically charged particles, similar to the terrestrial lightnings. Provided the current is intense enough, a powerful axially-symmetric impulse magnetic field is generated around the instantaneous virtual electric conductor. Such magnetic field is capable of magnetizing the planetesimals containing ferromagnetic components present in its vicinity to their saturation levels. As a result, planetesimals attract one another. This magnetically-driven aggregation suggests an important process possibly operational at an early stage of the planetary accretion. Based on both a classical model of electric conductor and the theory of Lienard--Wiechert electromagnetic potentials, our calculations show that the magnetic impulse associated with a discharge channel of a few cm in diameter carrying a charge of about 10^4 e reaches as high as 10 T. At these magnetic fields, the ferromagnetic planetesimals are easily magnetized to the saturation levels, producing compact clusters exhibiting permanent magnetic moments.