Bar dissolution and bulge formation

  • C. A. Norman
  • H. Hasan
  • J. A. Sellwood
Conference paper
Part of the International Astronomical Union / Union Astronomique Internationale book series (IAUS, volume 171)


We discuss the general classification of secular evolution in galaxies into terms of stellar dynamics. We present two-dimensional N-body simulations of a disk galaxy in which a central mass concentration is imposed after the formation of a strong bar. We show that the bar dissolves almost completely if the central mass concentration exceeds approximately 5% of the combined disk and bulge mass. This behavior can be understood in terms of previous work on single particle orbits (Hasan & Norman 1990, Hasan et al. 1993); the sustaining orbits aligned with the bar become stochastic as the Inner Lindblad resonance moves out past the minor axis of the bar. We present arguments that bar formation and subsequent thickening and dissolution will create a bulge-like stellar distribution from the central part of the disk. We discuss the predictions of such a model including the point that barred Ses with sufficient central mass concentrations should be building bulges now. We emphasize that bulges can come from a number of different mechanisms and we discuss the current evidence at both high and low redshift.


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Copyright information

© Springer Science+Business Media Dordrecht 1996

Authors and Affiliations

  • C. A. Norman
    • 1
  • H. Hasan
    • 2
  • J. A. Sellwood
    • 3
  1. 1.Space Telescope Science InstituteJohns Hopkins UniversityBaltimoreUSA
  2. 2.Space Telescope Science InstituteBaltimoreUSA
  3. 3.Dept. of Physics and AstronomyRutgers UniversityPiscatawayUSA

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