2008/02/03 by William F. Zech, Nicolas Lehner, J. Christopher Howk +2
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics and Star Formation Studies #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/587135
23 pages, 11 figures, 7 tables
arxiv created 2008/02/03 · openalex publication_date 2008/05/13 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
We present FUSE and STIS E140M observations of the post-AGB star ZNG 1 in the globular cluster Messier 5 ( l = 3.9°, b = + 47.7°; d = 7.5 kpc , z = + 5.3 kpc ). High-velocity absorption is seen in C IV, Si IV, O VI, and lower ionization species at LSR velocities of roughly –140 and –110 km s −1 . We conclude that this gas is not circumstellar on the basis of photoionization models and path length arguments. Thus, the high-velocity gas along the ZNG 1 sight line is the first evidence that highly ionized HVCs can be found near the Galactic disk. We measure the metallicity of these HVCs to be [O/H] = + 0.22 ± 0.10, the highest of any known HVC. Given the clouds' metallicity and distance constraints, we conclude that these HVCs have a Galactic origin. This sight line probes gas toward the inner Galaxy, and we discuss the possibility that these HVCs may be related to a Galactic nuclear wind or Galactic fountain circulation in the inner regions of the Milky Way.