The Hercules-Aquila cloud

V. Belokurov, N. W. Evans, E. F. Bell, M. J. Irwin, P. C. Hewett, S. Koposov, C. M. Rockosi, G. Gilmore, D. B. Zucker, M. Fellhauer, M. I. Wilkinson, D. M. Bramich, S. Vidrih, H. -W. Rix, T. C. Beers, D. P. Schneider, J. C. Barentine, H. Brewington, J. Brinkmann, M. HarvanekJ. Krzesinski, D. Long, K. Pan, S. A. Snedden, O. Malanushenko, V. Malanushenko

Research output: Contribution to journalArticlepeer-review


We present evidence for a substantial overdensity of stars in the direction of the constellations of Hercules and Aquila. The cloud is centered at a Galactic longitude of l ≈ 40° and extends above and below the Galactic plane by at least 50°. Given its off-centeredness and height, it is unlikely that the Hercules-Aquila cloud is related to the bulge or thick disk. More likely, this is a new structural component of the Galaxy that passes through the disk. The cloud stretches ~80° in longitude. Its heliocentric distance lies between 10 and 20 kpc so that the extent of the cloud in projection is ~20 kpc by ~15 kpc. It has an absolute magnitude of Mv = -13, and its stellar population appears to be comparable to, but somewhat more metal-rich than, M92.
Original languageEnglish
Pages (from-to)L89-L92
Number of pages4
JournalAstrophysical Journal
Issue number2
Publication statusPublished - 12 Feb 2007


  • galaxies : kinematics and dynamics
  • galaxies : structure
  • Galaxy : halo
  • Local Group

Cite this