Comparing Gaseous and Stellar Orbits in a Spiral Potential

Abstract

It is generally assumed that gas in a galactic disk follows closely non self-intersecting periodic stellar orbits. In order to test this common assumption, we have performed MHD simulations of a galactic-like disk under the influence of a spiral galactic potential. We also have calculated the actual orbit of a gas parcel and compared it to stable periodic stellar orbits in the same galactic potential and position. We found that the gaseous orbits approach periodic stellar orbits far from the major orbital resonances only. Gas orbits initialized at a given galactocentric distance but at different azimuths can be different, and scattering is conspicuous at certain galactocentric radii. Also, in contrast to the stellar behaviour, near the 4:1 (or higher order) resonance the gas follows nearly circular orbits, with much shorter radial excursions than the stars. Also, since the gas does not settle into a steady state, the gaseous orbits do not necessarily close on themselves.

8 pages, accepted for publication in MNRAS

References in corpus (3)

• Stellar Kinematic Constraints on Galactic Structure Models Revisited: Bar and Spiral Arm Resonances
• Errors in kinematic distances and our image of the Milky Way Galaxy
• Spiral stellar density waves and the flattening of abundance gradients in the warm gas component of spiral galaxies

Cited by in corpus (5)

• Gaseous Spiral Structure and Mass Drift in Spiral Galaxies
• The dynamical origin of the Local arm and the Sun's trapped orbit
• Modelling resonances and orbital chaos in disk galaxies. Application to a Milky Way spiral model
• Analysis of the spiral structure in a simulated galaxy
• Gas Dynamics in the Central Molecular Zone and its connection with the Galactic Bar