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Session 82 - Spirals & Irregulars.
Display session, Friday, January 09
Exhibit Hall,

[82.14] A Minor Merger Model for NGC 7479

S. Laine (U. Hertfordshire, United Kingdom)

The most salient features of NGC 7479 are its strong bar and an asymmetric spiral structure, dominated by the luminous western arm. HI observations have revealed severe velocity perturbations along the dominating arm, and a gaseous extension of the arm well beyond its end in optical images. The m=1 asymmetry can not be supported by the rotation curve of NGC 7479. The only feasible solution is that the asymmetry of the spiral arm structure, and perhaps even the strong bar, are the result of a recent external gravitational perturbation. However, no companion galaxies have been found that could have caused the observed structure in the recent past. Here I present numerical simulations made with a tree-SPH code to investigate the possibility that the outstanding structural components of NGC 7479 were created in a recent minor merger, where the companion has been disrupted by tidal forces from NGC 7479. The parameters of the interaction were varied to inspect their effect. These parameters include the halo mass of NGC 7479, the inclination of the companion orbit, the initial distance of the companion, the mass of the companion, the scale length of the companion, inclusion of a small bulge in NGC 7479 and the initial gas distribution in NGC 7479. The galaxies were built following the recipes given in the studies of minor mergers by Hernquist amp; Mihos (1995, ApJ, 448, 41).

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Program listing for Friday