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-...

One of the keys to interpreting the character and evolution of interstellar matter in the galaxy is understanding the distribution of the low density hot (10 5 K − 10 6 K) phase of the interstellar medium (ISM). This phase is much more difficult to observe than the cooler high density components of the ISM because of its low density and lack of easily observable tracers. Because gas of this tem...

In this paper we present some test results of our newly developed Multi-Phase Chemo-Dynamical Smoothed Particle Hydrodynamics (MP-CD-SPH) code for galaxy evolution. At first, we present a test of the “pure” hydro SPH part of the code. Then we describe and test the multi-phase description of the gaseous components of the interstellar matter. In this second part we also compare our condensation a...

We study the formation and evolution of several molecules in a collapsing interstellar cloud using a reasonably large reaction network containing more then four hundred atomic and molecular species. We employ a time dependent, spherically symmetric, hydrodynamics code to follow the hydrodynamic and chemical evolution of the collapsing cloud. The flow is assumed to be self-gravitating. We use tw...

The flux of neutrinos and photons originating from cosmic ray interactions with the interstellar medium in the galaxy is calculated based on current models for high energy particle interactions. The contribution from a possible dark matter halo of the galaxy is considered. The photon flux gets a non-trivial attenuation due to interactions with the cosmic background radiation. The neutrino fluxe...

Existing determinations show that n(C)/n(Fe) is more than a factor of 10 below solar in the atmospheres of three white dwarfs that appear to be externallypolluted. These results are not easily explained if the stars have accreted interstellar matter, and we re-interpret these measurements as evidence that these stars have accreted asteroids with a chondritic composition. Subject headings: plane...

Stars in the late stages of evolution are able to synthesize complex organic compounds with aromatic and aliphatic structures over very short time scales. These compounds are ejected into the interstellar medium and distributed throughout the Galaxy. The structures of these compounds are similar to the insoluble organic matter found in meteorites. In this paper, we discuss to what extent stella...

Implications of observed upper limits to the neutral hydrogen content of E and SO galaxies from Paper I are discussed. If gas shed by dying stars is completely retained by these galaxies and exists as H I, these upper limits will be exceeded in only lo9 yr for E's and SO'S and in only 2 x lo8 yr for NGC 4472. Evidently, gas either is hidden in some undetectable form or is removed from the inter...