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The Galactic Nature of High Velocity Cloud Complex WB

C. Thom·M. E. Putman·B. K. Gibson·N. Christlieb·C. Flynn·T. C. Beers·R. Wilhelm·Y. S. Lee
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Abstract

We have detected absorption lines from the High Velocity Cloud Complex WB in the spectrum of the star HE1048+0231. This detection sets an upper distance limit to the cloud of 8.8^{+2.3}_{-1.3} kpc. Non-detection (at >4 sigma confidence) in the star HE1138-1303 at 7.7 +/- 0.2 kpc sets a probable lower limit. The equivalent width of the CaII K line due to the HVC (114.6 +/- 4.4 mA) corresponds to a column density of 1.32 +/- 0.05 x 10^12 cm^-2. Using an HI spectrum from the Leiden/Argentine/Bonn survey, we calculated N(CaII)/N(HI) = 81 +/- 16 x 10^-9. These distance limits imply an HI mass limit of 3.8 x 10^5 Msun < M_HI < 4.9 x 10^5 Msun. The upper distance limit imposed by these observations shows that this HVC complex has a probable Galactic or circum-Galactic origin. Future metallicity measurements will be able to confirm or refute this interpretation.

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C. Thom, M. E. Putman, B. K. Gibson, N. Christlieb, C. Flynn, T. C. Beers, R. Wilhelm, Y. S. Lee. 2006-01-06. The Galactic Nature of High Velocity Cloud Complex WB. https://doi.org/10.1086/501005

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