High velocity clouds near the Magellanic Clouds

The high-velocity clouds and the Magellanic Clouds

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 with a mass of ∼ 3×109 M⊙, and that they are the product of a powerful “superwind” (about 10 58 ergs), which occurred in the Magellanic Clouds about 570 Myr...

Compact High Velocity Clouds

We summarize the observed properties of the CHVC population, which provide strong evidence for source distances in the range 200– 1000 kpc. At these distances, the population corresponds to strongly dark-matter dominated sub-dwarf galaxies still accreting onto the more massive Local Group systems. Recent searches for faint associated stellar populations have revealed red-giant candidates for wh...

The Magellanic Clouds Newsletter

Highly Ionized High Velocity Clouds

We have recently used the Hubble Space Telescope to study a pair of high velocity clouds in the direction of Mrk 509 that have unusual ionization properties. They exhibit strong C iv absorption with little or no low ion absorption or H i 21 cm emission. As the closest known analog to the outer diffuse halos of damped Lyα absorbers and the low N(H i) metal line absorption systems seen in the spe...

Superbubbles in the Magellanic Clouds

Superbubbles that result from the stellar winds and supernovae of OB associations probably play a fundamental role in the structure and energetics of the ISM in star-forming galaxies. Their influence may also dominate the relationship between the different interstellar gas phases. How do superbubbles form and evolve? How do they affect the local and global ISM? The Magellanic Clouds provide a s...