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Vertical Distribution of Galactic Disc Stars and Gas Constrained by a Molecular Cloud Complex
| Content Provider | Semantic Scholar |
|---|---|
| Copyright Year | 2001 |
| Abstract | We investigate the dynamical effects of a molecular cloud complex with a mass ∼ 10 7 M ⊙ and a size ∼ a few 100 pc, on the vertical distribution of stars and atomic hydrogen gas in a spiral galactic disc. Such massive complexes have now been observed in a number of spiral galaxies. The extended mass distribution in a complex, with an average mass density six times higher than the Oort limit, is shown to dominate the local gravitational field. This results in a significant redistribution or clustering of the surrounding disc components towards the mid-plane, with a resulting decrease in their vertical scale-heights. The modified, self-consistent stellar density distribution is obtained by solving the combined Poisson equation and the force equation along the z-direction for an isothermal stellar disc on which the complex is imposed. The effect of the complex is strongest at its centre, where the stellar mid-plane density increases by a factor of 2.6 and the vertical scale-height decreases by a factor of 3.4 compared to the undisturbed stellar disc. A surprising result is the large radial distance ∼ 500 pc from the complex centre over which the complex influences the disc, this is due to the extended mass distribution in a complex. The complex has a comparable effect on the vertical distribution of the atomic hydrogen gas in the galactic disc. This 'pinching' or constraining effect should be detectable in the nearby spiral galaxies, as for example has been done for NGC 2403 (Sicking 1997). Thus, the gravitational field of a complex results in local corrugations of the stellar and HI vertical scale-heights, and the galactic disc potential is highly non-uniform on scales of the inter-complex separation of ∼ 1 kpc. Running Title: Vertical constraining by a cloud complex |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://arxiv.org/pdf/astro-ph/0110331v1.pdf |
| Language | English |
| Access Restriction | Open |
| Subject Keyword | Cluster analysis Dynamical system Height Hydrogen Mass Density New General Catalogue Radial (radio) Spiral model Stars, Celestial Stellar (payment network) statistical cluster |
| Content Type | Text |
| Resource Type | Article |
