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, Ž Ivezić, P. Richter, U. J. Schwarz

Research output: Contribution to journalArticlepeer-review

130 Scopus citations

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 (3-14) × 10 6 M, and the complex represents a mass inflow of 0.1-0.25 M⊙ yr-1. We base our distance bracket on the detection of Ca ii absorption in the spectrum of the blue horizontal branch (BHB) star SDSS J120404.78+623345.6, in combination with a significant nondetection 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.

Original languageEnglish
Pages (from-to)L113-L116
JournalAstrophysical Journal
Volume670
Issue number2 PART 2
DOIs
StatePublished - 2007

Keywords

  • Galaxy: evolution
  • Galaxy: general
  • Galaxy: halo
  • Galaxy: structure
  • ISM: clouds
  • Stars: distances

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science

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