Modeling Encounters of Galaxies: The Case of NGC4449
| dc.creator | Theis, Christian | |
| dc.date | 1999-07-17 | |
| dc.date.accessioned | 2026-07-07T06:32:07Z | |
| dc.date.available | 2026-07-07T06:32:07Z | |
| dc.description | (abridged) Several N-body methods were combined in order to develop a method for the determination of the parameters of interacting galaxies. This method has been applied to the HI distribution of NGC4449. In a first step the fast restricted N-body models were used to confine a region in parameter space reproducing the main observational features. In a second step a genetic algorithm is introduced which allows for an automated search in parameter space as well as for a uniqueness test of special parameter sets. Using artificial data I show that the genetic algorithm reliably recovers orbital parameters. In the third step the results of the restricted N-body models are compared with detailed self-consistent N-body simulations. In the case of NGC4449 the applicability of the simple restricted N-body calculations is demonstrated. NGC4449 is an active star-forming dwarf galaxy of Magellanic type. From radio observations van Woerden et al. (1975) found an extended HI-halo around NGC4449 which is at least a factor of 10 larger than the optical diameter. More recently, Bajaja et al. (1994) and Hunter et al. (1998) discerned details in the HI-halo: a disc-like feature around the center of NGC4449 and a lopsided arm structure. In a series of simulations it is demonstrated that the main features can be obtained by a gravitational interaction between NGC4449 and DDO125, another nearby dwarf galaxy. According to these calculations the closest approach between both galaxies happened 350 Myr ago at a minimum distance of 25 kpc on a nearly parabolic orbit. In case of the encounter scenario, the dynamical mass of DDO125 should not be smaller than 10% of NGC4449's mass. The origin of this disc is still unclear, but it might be caused by a previous interaction. | |
| dc.description | 26 pages, 18 figures, to appear in Proc. of the Annual Meeting of the Astronomische Gesellschaft, Heidelberg, 1998, Rev. Mod. Astron. 12, a full PostScript version is available at http://www.astrophysik.uni-kiel.de/papers/papers_aghen/e-theis_99.html | |
| dc.identifier | https://arxiv.org/abs/astro-ph/9907237 | |
| dc.identifier | http://arxiv.org/abs/astro-ph/9907237 | |
| dc.identifier.uri | http://salesiana.dossiersoluciones.com/handle/123456789/98807 | |
| dc.subject | Astrophysics | |
| dc.title | Modeling Encounters of Galaxies: The Case of NGC4449 | |
| dc.type | text |