- Conference date: 20–22 October 2008
- Location: Annapolis (Maryland)
Highly‐ionized high‐velocity clouds have been studied for the last decade. Some lines of reasoning have suggested an extragalactic origin for these clouds, placing them near the outskirts of the Milky Way or Local Group, and some models have explored the possibility that they may be associated with dark matter minihalos. We have observed highly‐ionized HVCs toward the inner Galaxy globular cluster Messier 5 that appear to have a Galactic origin. We present FUSE and STIS observations of the post‐AGB star ZNG 1 in M 5 ( ). Absorption is seen in O VI, C IV, Si IV, and lower ionization species at LSR velocities near and Photoionization models and path length arguments rule out the possibility that this gas is circumstellar. The metallicity of these HVCs is the highest of any known HVC. Given the metallicity and distance constraints, we conclude that these HVCs have a Galactic origin. We hypothesize that these HVCs are part of a large‐scale circulation and may be related to a Galactic nuclear wind. A full description of this work can be found in Zech et al. (2008, ApJ, 679, 460).
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