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arXiv · 0710.3340

Distances to Galactic high-velocity clouds. Complex C

B. P. Wakker·D. G. York·J. C. Howk·J. C. Barentine·R. Wilhelm·R. F. Peletier·H. van Woerden·T. C. Beers·Z. Ivezic·P. Richter·U. J. Schwarz
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Abstract

We report the first determination of a distance bracket for the high-velocity cloud (HVC) complex C. Combined with previous measurements showing that this cloud has a metallicity of 0.15 times solar, these results provide ample evidence that complex C traces the continuing accretion of intergalactic gas falling onto the Milky Way. Accounting for both neutral and ionized hydrogen as well as He, the distance bracket implies a mass of 3-14x10^6 M_sun, and the complex represents a mass inflow of 0.1-0.25 M_sun/yr. We base our distance bracket on the detection of CaII absorption in the spectrum of the blue horizontal branch star SDSS J120404.78+623345.6, in combination with a significant non-detection toward the BHB star BS 16034-0114. These results set a strong distance bracket of 3.7-11.2 kpc on the distance to complex C. A more weakly supported lower limit of 6.7 kpc may be derived from the spectrum of the BHB star BS 16079-0017.

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B. P. Wakker, D. G. York, J. C. Howk, J. C. Barentine, R. Wilhelm, R. F. Peletier, H. van Woerden, T. C. Beers, Z. Ivezic, P. Richter, U. J. Schwarz. 2007-10-17. Distances to Galactic high-velocity clouds. Complex C. https://doi.org/10.1086/524222

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