Related papers: Where are the high velocity clouds?
Multiple SN explosions in disk galaxies efficiently evacuate gas and form cavities with the sizes and shapes of the surrounding envelopes determined by the total amount of injected energy and by the initial gas distribution. Such cavities…
We present two-dimensional MHD numerical simulations for the interaction of high-velocity clouds with both magnetic and non-magnetic Galactic thick gaseous disks. For the magnetic models, the initial magnetic field is oriented parallel to…
We combine HI 21cm observations of the Milky Way, M31, and the local galaxy population with QSO absorption-line measurements to geometrically model the three-dimensional distribution of infalling neutral gas clouds (HVCs) in the extended…
We present deep HI observations of three compact high-velocity clouds (CHVCs). The main goal is to study their diffuse warm gas and compact cold cores. We use both low- and high-resolution data obtained with the 100 m Effelsberg telescope…
Recent numerical simulations of the interstellar medium driven by energy input from supernovae and stellar winds indicate that HI clouds can be formed by compression in shock waves and colliding turbulent streams without any help from…
Observations with the Green Bank Telescope of 21cm HI emission from the high-velocity cloud Complex H suggest that it is interacting with the Milky Way. A model in which the cloud is a satellite of the Galaxy in an inclined, retrograde…
We present recent results on highly ionized gas in Galactic High-Velocity Clouds (HVCs), originally surveyed in OVI (Sembach et al. 2003). In a new FUSE/HST survey of SiII/III/IV (Shull et al. 2009) toward 37 AGN, we detected SiIII (lambda…
Most detected neutral atomic hydrogen (HI) at low redshift is associated with optically bright galaxies. However, a handful of HI clouds are known which appear to be optically dark and have no nearby potential progenitor galaxies, making…
We have used infrared and radio observations to search for a dwarf galaxy associated with the high-velocity cloud (HVC) known as Complex H. Complex H is a large (> 400 deg^2) and probably nearby (d = 27 kpc) HVC whose location in the…
Because isolated high-velocity clouds (HVCs) are found at great distances from the Galactic radiation field and because they have subsolar metallicities, there have been no detections of dust in these structures. A key problem in this…
To gain insight into four highly ionized high-velocity clouds (HVCs) discovered by Sembach et al. (1999), we have analyzed data from the Hubble Space Telescope (HST) and Far Ultraviolet Spectroscopic Explorer (FUSE) for the PKS 2155-304 and…
Intermediate-velocity clouds (IVCs) are HI halo clouds that are likely related to a Galactic fountain process. In-falling IVCs are candidates for the re-accretion of matter onto the Milky Way. We study the evolution of IVCs at the disk-halo…
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…
Whether High Velocity Clouds (HVCs) can form by condensation of the hot ($T \sim 10^6 \, {\rm K}$) Galactic corona as a consequence of thermal instabilities has been controversial. Here we re-examine this problem and we suggest that…
We present deep Halpha spectroscopy towards several high-velocity clouds (HVCs) which vary in structure from compact (CHVCs) to the Magellanic Stream. The clouds range from being bright (~640 mR) to having upper limits on the order of 30 to…
There is mounting evidence for an extra-planar gas layer around the Milky Way disk, similar to the anomalous HI gas detected in a few other galaxies. As much as 10% of the gas may be in this phase. We analyze HI clouds located in the…
We here explore the effects of the SN explosions into the environment of star-forming galaxies like the Milky Way. Successive randomly distributed and clustered SNe explosions cause the formation of hot superbubbles that drive either…
Potential condensed clouds of gas in the Galactic halo are examined in the context of the recent models of cooling, fragmenting clouds building up the baryonic mass of the Galaxy. 582 high-velocity clouds (HVCs) are defined as the potential…
We report the discovery of molecular hydrogen absorption in a Galactic high-velocity cloud (HVC) in the direction of the Large Magellanic Cloud. For the same HVC we derive an iron abundance which is half of the solar value. Thus, all…
A model is proposed for determining the distances to falling interstellar clouds in the galactic halo by measuring the cloud velocity and column density and assuming a model for the vertical density distribution of the Galactic interstellar…