Several of the triggering mechanisms discussed above are illustrated in the Antenna galaxy, which is a merger. Figure 6 shows the Antenna labeled with suggested analogies: spiral arm shock triggering with downstream rings, beads on a string from gravitational collapse in a filament, radial inflow in elongated, bar-like regions, and a converging flow that produces extreme compressions between the two gas disks.
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Figure 6. HST image of the Antenna galaxy showing several types of triggering discussed in the text. |