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Paper: Distances and Metallicities of High-Velocity Clouds
Volume: 166, Stromlo Workshop on High-Velocity Clouds
Page: 1
Authors: van Woerden, Hugo; Peletier, Reynier F.; Schwarz, Ulrich J.; Wakker, Bart P.; Kalberla, Peter M. W.
Abstract: Distance and metallicity hold the key to our understanding of the physical properties and origins of HVCs. We review the problems and results of determinations of distance and metallicity based on the presence or absence, and strength, of appropriate absorption lines in the spectra of stars at different distances and of extragalactic background sources. Upper or lower distance limits are available for several HVCs, and indicate various locations with respect to the major structural components of the Galaxy. The only distance bracket available, 4<d<10 kpc for Complex A, places this HVC firmly in the Galactic Halo. Metallicity values of 0.1, 0.25 and 1.0 times solar, based on SII\ absorption lines, have been measured for three HVCs. The wide ranges found for distance, location and metallicity suggest that HVCs may have a variety of origins.
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