Hoag's Object: Remnant of a Galaxy's Vanished Bar
Abstract
The beautiful ringed Hoag's object, named after its discoverer, is a puzzling galaxy. Because of the roundness of its ring-like structure, it has been proposed to be a collisional ring galaxy; however, there is no obvious nearby culprit galaxy that could have collided with it. Considering an alternative hypothesis, we study the development of the observed structure via a weak turning bar perturbation. However, there is presently no obvious bar present and rings produced by bars are typically oval. On the basis of much recent theoretical work improving understanding of bar evolution, we assume the bar grows and then vanishes. In simulations of a disk of particles, perturbed by such a bar turning in the disk plane, we find disk material is gathered into a core, leaving an empty void, and also concentrated in a surrounding circular ring in the disk. This mimics the morphology of Hoag's object. This interesting object may thus provide evidence that bars can appear and then vanish in disk galaxies.
- Publication:
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AAS/Division of Dynamical Astronomy Meeting #40
- Pub Date:
- May 2009
- Bibcode:
- 2009DDA....40.0704B