NGC 5128, J.L. Sersic, Atlas de Galaxias Australes, 1968
NGC 253, J.L. Sersic, Atlas de Galaxias Australes, 1968
1st Extragalactic Astronomy Meeting, 1975, J.L. Sersic, T.G. Catellanos, P. Kaufman
NGC 2442, J.L. Sersic, Atlas de Galaxias Australes, 1968
2nd Extragalactic Astronomy Meeting, 1987
NGC 2997, J.L. Sersic, Atlas de Galaxias Australes, 1968
3rd Extragalactic Astronomy Meeting, 1996
NGC 55, J.L. Sersic, Atlas de Galaxias Australes, 1968

Elena D’Onghia

USA – University of Wisconsin-Madison

When do disks form bars?

Abstract: Using high-resolution N-body simulations, we have investigated a stellar disk’s stability to a bar mode. To date, there is no convincing global criterion regulating the formation of bars in disk galaxies. Here we do not assume that the disk is purely self-gravitating but exists in the potential of an external force field and its self-gravity. The simulations show that two global
dimensionless parameters in our study appear to control the instability to m=2 modes. Our analysis shows that these two parameters define a plane with regions of stable and unstable disks to the bar formation. Unlike the Toomre Q parameter, which regulates the disk stability locally, the identified parameters in our study are global and play a crucial role in the stability of a broad class of disks to bar formation at all scales. The criterion should be applicable to high redshift disks.

PROGRAM