Non-equilibrium level populations of molecular hydrogen - I. Uniform density, static clouds

Equilibrium and dynamics of uniform density ellipsoidal non-neutral plasmas

When a single-species plasma is confined in a harmonic Penning trap at cryogenic temperature, the thermal equilibrium is approximately a uniform density spheroid (ellipsoid of revolution). Normal modes corresponding to quadrupole excitations of this plasma have recently been measured. In this paper, nonlinear equations of motion are derived for these quadrupole oscillations. For large amplitude...

Molecular Hydrogen Excitation in Gas Clouds

Molecular Hydrogen in High-Velocity Clouds

We present Far Ultraviolet Spectroscopic Explorer (FUSE) observations of interstellar molecular hydrogen (H2) in two Galactic high-velocity clouds (HVCs). Molecular hydrogen absorption is detected in the Magellanic Stream (abundance ∼ 0.3 solar) toward the Seyfert galaxy Fairall 9 in the lowest three rotational states (J = 0− 2) at vLSR = +190 kms , yielding a total H2 column density of log N(H...

Registration of Non-Uniform Density 3D Point Clouds using Approximate Surface Reconstruction

3D laser scanners composed of a rotating 2D laser range scanner exhibit different point densities within and between individual scan lines. Such non-uniform point densities influence neighbor searches which in turn may negatively affect feature estimation and scan registration. To reliably register such scans, we extend a state-of-the-art registration algorithm to include topological informatio...

Simulating the formation of molecular clouds. I. Slow formation by gravitational collapse from static initial conditions

We study the formation of H2 in the ISM, using a modified version of the astrophysical magnetohydrodynamical code ZEUS-MP that includes a nonequilibrium treatment of the formation and destruction of H2. We examine two different approximations to treat the shielding of H2 against photodissociation: a local approximation, which gives us a solid lower bound on the amount of shielding, and a method...