The Jeans instability of infinite homogeneous, self-gravitating quantum plasma is investigated under the assumption of optically thick medium and black body radiation. The general dispersion relation is obtained and the condition of instability is discussed.

A recent model for the stellar initial mass function (IMF), in which the stellar masses are randomly sampled down to the thermal Jeans mass from hierarchically structured pre-stellar clouds, predicts that regions of ultra-cold CO gas, such as those recently found in nearby galaxies by Allen and collaborators, should make an abundance of Brown Dwarfs with relatively few normal stars. This result...

It is shown that the interaction of helicity-1 waves of gravity and matter in a thin slab configuration produces new types of instabilities. Indeed, a spin2 helicity-1 mode interacts strongly with the shear motion of matter. This mode is unstable above a critical wavelength, λc = √ πc2/2Gρ. This should be compared with Jeans wavelength, λJ = √ πcs/Gρ, where cs is the sound speed. The two instab...

In this paper we study a simple model consisting of a dilute fully ionized plasma in the presence of the gravitational and a constant magnetic field to analyze the propagation of hydromagnetic instabilities. In particular we show that the so called Jeans instability is in principle affected by the presence of the magnetic field. A brief discussion is made attempting to assess this influence in ...

The ratio of the Bondi and Jeans lengths is used to develop a cloud-accretion model that describes both an inner Bondi-type regime where gas pressure is balanced by the gravity of a central star and an outer Jeans-type regime where gas pressure is balanced by gas self-gravity. The gas density profile provided by this model makes a smooth transition from a wind-type inner solution to a Bonnor-Eb...