The Spiral Density Wave in a Thick Galactic Disk
Abstract
Models of the thick galactic gaseous disk in magnetohydrostatic equilibria are presented. The observational evidence of the vertical structure in our Galaxy and other spirals is briefly discussed. Then, the disk response to different large scale perturbations is described. Finally, the action of the spiral density wave (SDW) in such a disk is calculated. It is found that the inclusion in the models of the extended Galactic warm ionized layer alters the conventional view of the SDW scenario: the shock, and a prominent structure of large column density extend well above the spiral arm. It is argued that if the SDW triggers star formation, it should do it not only at midplane, but at high Galactic latitudes as well. The resulting structure resembles a hydraulic jump, or bore, in which gas entering the arm rises, accelerates above the arm and lands onto a large downfall region downstream of the arm. For more details of this work see Martos et al. 1999, ApJ, 526, L89.
- Publication:
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Revista Mexicana de Astronomia y Astrofisica Conference Series
- Pub Date:
- May 2000
- Bibcode:
- 2000RMxAC...9..344M