The Dwingeloo/Villa-Elisa HI Survey - the first Super-Sensitive View of Galactic Structure and Dynamics
Final Report Abstract
90% of the H I in the Milky Way exists as an extended exponential disk. This disk is flaring, with a scale-height increasing exponentially with radial distance. The disk is warped but on average its shape is well defined out to radii of 35 kpc. The size of the disk is understandable in terms of a mass model with an oblate mass distribution in the inner part, turning into a prolate distribution at large distances. The homogeneous H I disk terminates at a distance where the transition between oblate and prolate distribution takes place. Mass models with a spheroidal mass distribution are incompatible with the H i observations. The dominant part of the disk is embedded in a hot plasma, but also surrounded by a patchy distribution of highly turbulent H I gas clumps with a low filling factor. This outer part may be considered as a thick disk component. The clumps of this extraplanar component are approximately co-rotating with the disk, but slightly lagging behind. The cores are cold and have dimensions of about 1 pc. They are surrounded by warmer envelopes. On average there is pressure equilibrium between the different gas phases. Only a fraction of the clumps is explainable as caused by Galactic fountain events. The Milky Way H I disk is highly turbulent, with a large number of spurs and filaments extending to high altitudes. The specific energy density of the extra-planar gas exceeds that of the disk by an Order of magnitude.
Publications
- 2006, ApJ, 638, 196
McClure-Griffiths, N. M., Ford, A., Pisano, D. J., Gibson, B. K., Staveley-Smith, L., Calabretta, M. R., Dedes, L., & Kalberla, P. M. W .
- 2007, A&A, 469, 511
Kalberla, P. M. W., Dedes, L., Kerp, J., & Haud, U.
- 2008, A&A, 487, 951
Kalberla, P. M. W., & Dedes, L.
- 2008, A&A, 491, L45
Dedes, L., Dedes, C., & Kalberla, P. W . M .
- 2008, ApJ, 688, 290
Ford, H. A., McClure-Griffiths, N. M., Lockman, F. J., Bailin, J., Calabretta, M. R., Kalberla, P. M. W., Murphy, T., & Pisano, D. J.
- 2008, Mapping the Galaxy and Nearby. Galaxies, 317
Dedes, L., & Kalberla, P.
- 2008. The cloudy HI halo of the Milky Way, PhD thesis, University of Bonn
Dedes L.
