The Formation and Early Evolution of Protostars and Protoplanetary Disks

Abstract

We discuss the formation and early evolution of protostars and protoplanetary disks. Recent advances in theoretical modelling with resistive magnetohydrodynamical codes with various numerical techniques has dramatically improved our understanding on the driving of outflows/jets and the formation of protoplanetary disks. The circumstellar disk is born in a “dead zone,” a region that is de-coupled from the magnetic field. The outer radius of the disk increases with the outer boundary of the dead zone during the phase of gas accretion from the envelope of the molecular cloud core. The rapid increase of the disk size occurs after the depletion of the envelope. Circumstellar disks remain massive in their formation phase, and are subject to gravitational instability, even at 10 AU from the central stars.