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High-velocity clouds and extended gaseous galactic halos

Published online by Cambridge University Press:  17 September 2012

B.P. Wakker
B.P. Wakker*
Affiliation:
Department of Astronomy, University of Wisconsin, 475 N. Charter St., Madison, WI 53705, USA. e-mail: [email protected];
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Abstract

This contribution summarizes some recent results concerning gas in Galaxy halos. In the past few years, distances have been determined for six high-velocity clouds (HVCs), including the second largest, complex C. The derived distances range from about 2 to 10 kpc, placing these HVCs in the near Galactic halo, but far above the Galactic plane. Distances of ∼10 kpc were determined to three different concentrations in Complex C, implying a mass of ∼5 × 107M⊙; this cloud is known to have a metallicity of ∼0.15 solar, and represents an inflow of 0.15–0.25 M⊙ yr−1 of low-metallicity material. A statistical analysis of the sky and velocity distribution of the ∼200 small HVCs shows that they probably form a population of clouds orbiting the Milky Way, with distances up to 80 kpc, and a radial inflow component of 50 km s−1. A study of 115 Lyα and 14 O VI absorption lines at redshifts z < 0.017 (v < 5000 km s−1) in the spectra of 76 AGNs shows that half of the intergalactic Lyα absorption lines originate within 450 kpc of galaxies. The amount of gas inside this distance is a factor 2–4 more than the total amount of mass inside the galaxies.

Type
Research Article
Information
European Astronomical Society Publications Series , Volume 56: The Role of the Disk-Halo Interaction in Galaxy Evolution: Outflow vs. Infall? , 2012 , pp. 257 - 265
Copyright
© EAS, EDP Sciences, 2012

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References

Beers, T.C., Wilhelm, R., Doinidis, S.P., & Mattson, C.J., 1996, ApJS, 103, 433CrossRef
Brown, W.R., Geller, M.J., Kenyon, S.J., et al., 2004, AJ, 127, 1555CrossRef
Cutri, R.M., et al., 2003,2MASS All Sky Catalog of Point Sources (VizieR Online Data Catalog), 2246Google Scholar
Danforth, C.W., & Shull, J.M., 2008, ApJ, 679, 643CrossRef
Fox, A.J., Savage, B.D., Wakker, B.P., et al., 2004, ApJ, 602, 738CrossRef
Hulsbosch, A.N.M., & Wakker, B.P., 1988, A&AS, 75, 191
Kukarkin, B.V., et al., 1969, 1970, General Catalogue of Variable Stars, Third Edition, Volumes I and II (Moscow: Sternberg Institute)Google Scholar
Lehner, N., Savage, B.D., Richter, P., et al., 2007, ApJ, 658, 680CrossRef
Morras, R., Bajaja, E., Arnal, E.M., & Pöppel, W.G.L., 2000, A&AS, 142, 25
Penton, S.V., Stocke, J.T., & Shull, J.M., 2002, ApJ, 565, 720CrossRef
Sancisi, R., Fraternali, F., Oosterloo, T.A., & van der Hulst, J.M., 2008, A&ARv, 15, 189
Schwarz, U.J., Wakker, B.P., & van Woerden, H., 1995, A&A, 302, 364
Sembach, K.R., Savage, B.D., & Massa, D., 1991, ApJ, 372, 81CrossRef
Shaw, C.R., Bates, B., Kemp, S.N., et al., 1996, ApJ, 473, 849CrossRef
Thom, C., Putman, M.E., Gibson, B.K., et al., 2006, ApJ, 638, L97CrossRef
Tripp, T.M., Sembach, K.R., Bowen, D.V., et al., 2008, ApJS, 177, 39CrossRef
van Woerden, H., Schwarz, U.J., Peletier, R.F., Wakker, B.P., & Kalberla, P.M.W., 1999, Nature, 400, 138CrossRef
Wakker, B.P., et al., 2003, ApJS, 146, 1CrossRef
Wakker, B.P., York, D.G., Howk, J.C., et al., 2007, ApJ, 670, L113CrossRef
Wakker, B.P., York, D.G., Wilhelm, R., et al., 2008, ApJ, 672, 298CrossRef
Wakker, B.P., & van Woerden, H., 1997, ARA&A, 35, 217CrossRef
Wakker, B.P., & Savage, B.D., 2009, ApJS, in press
Wilhelm, R., Beers, T.C., & Gray, R.O., 1999, AJ, 117, 2308CrossRef
York, D.G., et al., 2000, AJ, 120, 1579CrossRef