Related papers: Formation of Gaseous Shells
Lenticular galaxies are generally thought to have descended from spirals via morphological transformation, although recent numerical simulations have shown that minor or even major merger can also lead to an S0-like remnant. These…
The interstellar medium is characterised by an intricate filamentary network which exhibits complex structures. These show a variety of different shapes (e.g. junctions, rings, etc.) deviating strongly from the usually assumed cylindrical…
It is currently believed that galaxies were assembled via chaotic hierarchical mergers between massive cold dark matter halos, in which baryonic star forming matter was embedded. One would therefore expect the properties of individual…
Planetary nebulae (PNe) are circumstellar gas ejected during an intense mass-losing phase in the the lives of asymptotic giant branch stars. PNe have a stunning variety of shapes, most of which are not spherically symmetric. The debate over…
The discovery of young globular clusters in merging galaxies and other environments provides an opportunity to study directly the process of globular cluster formation. Empirically it appears that globular cluster formation occurs…
In this review, I present the case for how massive stars may form through stellar collisions. This mechanism requires very high stellar densities, up to 4 orders of magnitude higher than are observed in the cores of dense young clusters. In…
The large number of exoplanets found to orbit their host stars in very close orbits have significantly advanced our understanding of the planetary formation process. It is now widely accepted that such short-period planets cannot have…
The results of a numerical investigation of fluidized beds of spherical particles in a narrow vertical cylindrical pipe, with particular attention to the spontaneous settling along the wall, are reported. Starting from a steady fluidized…
We consider the most commonly occurring circumstances which apply to galaxies, namely membership in galaxy groups of about $10^{13}h^{-1} M_\odot$ total mass, and estimate the accompanying physical conditions of intergalactic medium (IGM)…
Evidence for the accretion of cold gas in galaxies has been rapidly accumulating in the past years. HI observations of galaxies and their environment have brought to light new facts and phenomena which are evidence of ongoing or recent…
We examine the tidal disruption of satellite galaxies in a cosmological simulation of the formation of a disk galaxy in the $\Lambda$CDM scenario. We find that the disruption of satellite galaxies in orbits roughly coplanar with the disk…
The gravitational instability of expanding shells is discussed. Linear and nonlinear terms are included in an analytical solution in the static and homogeneous medium. We discuss the interaction of modes and give the time needed for…
We present a new model for the formation of stellar halos in dwarf galaxies. We demonstrate that the stars and star clusters that form naturally in the inner regions of dwarfs are expected to migrate from the gas rich, star forming centre…
I review evidence that galaxies form from gas that falls into potential wells cold, rather than from virialized gas, and that formation stops once an atmosphere of trapped virialized gas has accumulated. Disk galaxies do not have such…
Interstellar dust is spread in galaxies over large scales, often far beyond the stellar disks. Several mechanisms can be responsible for carrying the dust both in the vertical and radial directions, producing in general different spatial…
Star formation in interacting systems may take place in various locations, from the dust--enshrouded core of Ultraluminous Infrared Galaxies to more unusual places such as the debris of colliding galaxies expelled into the intergalactic…
Galactic collisions trigger a number of phenomena, such as transportation inward of gas from distances of up to kiloparsecs from the center of a galaxy to the nuclear region, fuelling a central starburst or nuclear activity. The inverse…
Triggered star formation in bright rims and shells is reviewed. Shells are commonly observed in the Milky Way and other galaxies, but most diffuse shells seen in HI or the infrared do not have obvious triggered star formation. Dense…
Gravitational interactions and mergers are shaping and reshaping galaxies throughout the observable universe. While observations of interacting galaxies at low redshifts yield detailed information about the processes at work, observations…
Tidal interactions between disc galaxies and low mass companions are an established method for generating galactic spiral features. In this work we present a study of the structure and dynamics of spiral arms driven in interactions between…