We present the hydrodynamic evolution in three-dimensions of a spherical bubble embedded in a less dense uniform ambient medium as it interacts with a Mach 10 planar shock. This scenario is an idealized model of the interaction of an interstellar cloud with a large supernova remnant. A third order Godunov numerical algorithm and 5.2 million grid points are used to resolve the complex ow eld whi...

We have used the Deep Survey telescope of EUVE to investigate shadows in the diffuse EUV/Soft X-Ray background cast by clouds in the interstellar medium. We confirm the existence of a shadow previously reported, and provide evidence for two new shadows. We used IRAS data to identify the clouds producing these shadows and to determine their optical depth to EUV radiation. The EUV-absorbing cloud...

A primary goal of the FUSE mission is to understand the origin of the O VI ion in the interstellar medium of the Galaxy and the Magellanic Clouds. Along sightlines to OB-type stars, these interstellar components are usually blended with O VI stellar wind profiles, which frequently vary in shape. In order to assess the effects of this time-dependent blending on measurements of the interstellar O...

Accretion flow in a contracting magnetized interstellar cloud was studied using magnetohydrodynamical simulations and a nested grid technique. First, the interstellar magnetized cloud experiences a “runaway collapse” phase, in which the central density increases drastically within a finite time scale. Finally, it enters an accretion phase, in which inflowing matter accretes onto a central high-...

A method for following fragmentation simulations further in time using smoothed particle hydrodynamics (SPH) is presented. In a normal SPH simulation of the collapse and fragmentation of a molecular cloud, high-density regions of gas that form proto-stars are represented by many particles with small separations. These high-density regions require small time steps, limiting the time for which th...

Water (H2O) ice is an important solid constituent of many astrophysical environments. To comprehend the role of such ices in the chemistry and evolution of dense molecular clouds and comets, it is necessary to understand the freeze-out, potential surface reactivity, and desorption mechanisms of such molecular systems. Consequently, there is a real need from within the astronomical modelling com...

Abstract Interstellar objects (ISOs), the parent population of 1 i /‘Oumuamua and 2 /Borisov, are abundant in interstellar medium Milky Way. This means that medium, including molecular-cloud regions, has three components: gas, dust, ISOs. From observational constraints field density ISOs drifting solar neighborhood, we infer a typical molecular cloud 10 pc diameter contains some 18 At sizes ran...

Context. Low-energy cosmic rays are a fundamental source of ionization for molecular clouds, influencing their chemical, thermal and dynamical evolution. Aims. The purpose of this work is to explore the possibility that a low-energy component of cosmic-rays, not directly measurable from the Earth, can account for the discrepancy between the ionization rate measured in diffuse and dense interste...

Formation of interstellar clouds as a consequence of thermal instability is studied using twodimensional two-fluid magnetohydrodynamic simulations. We consider the situation of converging, supersonic flows of warm neutral medium in the interstellar medium that generate a shocked slab of thermally unstable gas in which clouds form. We found, as speculated in paper I, that in the shocked slab mag...