Originally Posted by tusenfem

Jupiter-like, pulsar-like, ....

Anywhere that electrons are accelerated electromagnetic radiation will be emitted. In the case of acceleration at the magnetic poles of planets and stars (including compact objects) the emission is in the radio frequency band. One of the methods is "linear acceleration emission" which has been proposed for radio wave emission from electrostatic double layers. Mostly, all mechanisms are dependent on magnetic field strength and rotation rate of the object as the electric field doing the acceleration is basically the vxB electric field.

One of the first ones (I think) to do this for pulsars was Don Melrose (with a time varying electric field) and is described in his excellent book (if you are a math buff that is) Instabilities in Space and Laboratory Plasmas.

The size of the object will not have much influence, apart from maybe creating a larger generation area at the poles, but that would be dependent again on the magnetic field strength, yadayadayada ....