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We present new observational results on high-velocity clouds (HVCs) based on an analysis of the Leiden/Dwingeloo HI survey. We cataloged all HVCs with NHI > 1 10^19 cm^-2 and found 252 clouds that form a representative flux limited sample.…
We present two sets of grid-based hydrodynamical simulations of high-velocity clouds (HVCs) traveling through the diffuse, hot Galactic halo. These HI clouds have been suggested to provide fuel for ongoing star formation in the Galactic…
High-velocity clouds (HVC), fast-moving ionized and neutral gas clouds found at high galactic latitudes, may play an important role in the evolution of the Milky Way. The extent of this role depends sensitively on their distances and total…
Recent observations of high velocity clouds (HVCs) have revealed compression fronts and tail shaped features of HI suggesting that they are interacting with external medium. We perform 3-D hydro-dynamical simulations of HVCs moving through…
We present some developments in determining H-alpha distances to high-velocity clouds (HVCs) in the Galactic halo. Until recently, it was difficult to assess the nature and origin of HVCs because so little was known about them. But now…
High velocity gas that does not conform to Galactic rotation is observed throughout the Galaxy's halo. One component of this gas, HI high velocity clouds (HVCs), have attracted attention since their discovery in the 1960s and remain…
We suggest that the high--velocity clouds (HVCs) are large clouds, with typical diameters of 25 kpc and containing 5e7 solar masses of neutral gas and 3e8 solar masses of dark matter, falling onto the Local Group; altogether the HVCs…
High-velocity clouds (HVCs) are neutral or ionised gas clouds in the vicinity of the Milky Way that are characterised by high radial velocities inconsistent with participation in the regular rotation of the Galactic disc. Previous attempts…
Arecibo mapping is reported of the neutral hydrogen distribution along selected directions out from the centers of two small High Velocity Clouds (HVC), W486 and W491. Both HVCs have a small inner region where the neutral hydrogen column…
Models that reproduce the observed high-velocity clouds (HVCs) also predict clouds at lower radial velocities that may easily be confused with Galactic disk (|z| < 1 kpc) gas. We describe the first search for these low-velocity halo clouds…
High-velocity clouds (HVCs) are multi-phase gas structures whose velocities (|v_LSR|>100 km/s) are too high to be explained by Galactic disk rotation. While large HVCs are well characterized, compact and small HVCs (with HI angular sizes of…
From an analysis of the sky and velocity distributions of the high-velocity clouds (HVCs) we show that the majority of the HVCs has a common origin. We conclude that the HVCs surround the Galaxy, forming a metacloud of 300 kpc in size and…
High-velocity clouds (HVCs) are clouds of HI seen around the Milky Way with velocities inconsistent with Galactic rotation, have unknown distances and masses and controversial origins. One possibility is that HVCs are associated with the…
The results of the interaction between the Milky Way and the Magellanic Clouds are revealed through several high velocity complexes which are connected to the Clouds. The exact mechanism of their formation is under some debate, but they…
We observed two compact high-velocity clouds HVC 291+26+195 and HVC 297+09+253 to analyse their structure, dynamics, and physical parameters. In both cases there is evidence for an association with the Leading Arm of the Magellanic Clouds.…
The Arecibo HI Strip Survey probed the halos of ~300 cataloged galaxies and the environments of ~14 groups with sensitivity to neutral hydrogen masses > 10^7 M_sun. The survey detected no objects with properties resembling the High Velocity…
High-velocity clouds (HVCs), which are gas clouds moving at high velocity relative to the galactic disk, may play a critical role in galaxy evolution, potentially supplying gas to the disk and triggering star formation. In this study, we…
Significant numbers of high-velocity HI clouds (HVCs) have now been detected in H-alpha, with a subset seen in low ionization lines (e.g. [NII]). It was originally hoped that the observed H-alpha strength would provide a distance constraint…
In the spectra of 139 early-type Large Magellanic Cloud (LMC) stars observed with FUSE and with deep radio Parkes HI 21-cm observations along those stars, we search for and analyze the absorption and emission from high-velocity gas at…
We combine the catalogs of compact high-velocity HI clouds extracted from the LDS and HIPASS surveys and analyze the all-sky properties of the ensemble. Five principal observables are defined for the CHVC population: (1) the spatial…