Context. Supersonic turbulence in molecular clouds is a dominant agent that strongly affects the clouds’ evolution and star formation activity. Turbulence may be initiated and maintained by a number of processes, acting at a wide range of physical scales. By examining the dynamical state of molecular clouds, it is possible to assess the primary candidates for how the turbulent energy is injecte...

Three-dimensional fractal models on grids of ∼ 200 pixels are generated from the inverse Fourier transform of noise with a power law cutoff, exponentiated to give a log normal distribution of density. The fractals are clipped at various intensity levels and the mass and size distribution functions of the clipped peaks and their subpeaks are determined. These distribution functions are analogous...

Observations of interstellar gas and dust towards nearby stars and within the solar system show that the Sun is embedded in a warm diffuse partiallyionized cloud. This cloud is the leading edge of a flow of interstellar matter (ISM) through our Galactic neighborhood. Interstellar matter sets the boundary conditions of the heliosphere and astrospheres of extra-solar planetary systems. Moreover, ...

We develop a formalism wherein the solution of the equations of equilibrium for a self-gravitating, magnetized interstellar cloud may be accomplished analytically, under the only hypotheses that (a) the cloud is scale-free, and (b) is electrically neutral. All variables are represented as series of scalar and vector spherical harmonics, and the equilibrium equations are reduced to a set of coup...

The Taurus molecular cloud complex is the paradigm for quiescent, low-density, isolated star formation. Yet the age distribution of its stellar population indicates that star formation is a rapid and dynamic process, inconsistent with the old picture of magnetically-controlled protostel-lar cloud collapse. Instead, Taurus seems to have formed stars in a manner qualitatively consistent with the ...

The thermal and chemical phases of the cool component of interstellar gas are discussed. Variations with galactocentric radius and from galaxy to galaxy are mostly the result of changes in the ambient interstellar pressure and radiation field. Interstellar structure that is hierarchical or fractal in the cloudy parts and has large and connected empty regions between these clouds is probably the...

Molecular clouds are expected to emit non-thermal radiation due to cosmic ray interactions in the dense magnetized gas. Such emission is amplified if a cloud is located close to an accelerator of cosmic rays and if cosmic rays can leave the accelerator and diffusively reach the cloud. We consider the situation in which a molecular cloud is located in the proximity of a supernova remnant which i...

The interstellar cloud surrounding the solar system regulates the galactic environment of the Sun and constrains the physical characteristics of the interplanetary medium. This paper compares interstellar dust grain properties observed within the solar system with dust properties inferred from observations of the cloud surrounding the solar system. Properties of diffuse clouds in the solar vici...

The interstellar cloud surrounding the solar system regulates the galactic environment of the Sun and constrains the physical characteristics of the interplanetary medium. This paper compares interstellar dust grain properties observed within the solar system with dust properties inferred from observations of the cloud surrounding the solar system. Properties of diffuse clouds in the solar vici...