The hall instability of weakly ionized, radially stratified, rotating disks

Edward Liverts, Michael Mond, Arthur D. Chernin

Research output: Contribution to journalArticlepeer-review

12 Scopus citations

Abstract

Cool weakly ionized gaseous rotating disks are considered by many models to be the origin of the evolution of protoplanetary clouds. Instabilities against perturbations in such disks play an important role in the theory of the formation of stars and planets. Thus, a hierarchy of successive fragmentations into smaller and smaller pieces as apart of the Kant-Laplace theory of formation of the planetary system remains valid also for contemporary cosmogony. Traditionally, axisymmetric magnetohydrodynamic (MHD) and, recently, Hall-MHD instabilities have been thoroughly studied as providers of an efficient mechanism for radial transfer of angular momentum and of radial density stratification, In the current work, the Hall instability against nonaxisymmetric perturbations in compressible rotating fluid in external magnetic field is proposed as a viable mechanism for the azimuthal fragmentation of the protoplanetary disk and, thus, perhaps initiates the road to planet formation. The Hall instability is excited due to the combined effect of the radial stratification of the disk and the Hall electric field, and its growth rate is of the order of the rotation period. This family of instabilities is introduced here for the first time in an astrophysical context.

Original languageEnglish
Pages (from-to)1226-1231
Number of pages6
JournalAstrophysical Journal
Volume666
Issue number2 I
DOIs
StatePublished - 1 Jan 2007

Keywords

  • Instabilities
  • MHD
  • Planetary systems: protoplanetary disks

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