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Delayed formation of bulges by dynamical processes

Published online by Cambridge University Press:  07 August 2017

Daniel Pfenniger
Daniel Pfenniger*
Affiliation:
Geneva Observatory, CH-1290 Sauverny, Switzerland September 29, 1992

Abstract

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Two mechanisms involving purely dynamical processes can lead to the formation of a bulge after its disc: 1) small bulges (1 – 2 kpc), including box-shaped bulges and mildly triaxial bulges, can result from the formation and destruction of a bar; 2) big bulges (> 2kpc) à la Sombrero can grow following the accretion of small satellites. Fully consistent N-body simulations show that the fraction of galaxy mass accreted in this way needs to be larger than about 5%. Less accretion does not create smaller bulges, but heats the whole disc. These dynamical effects transforming Hubble types from SB to SA and vice-versa over ≈ 1 – 2 Gyr also indicate, by the secular growth of bulges, a general sense of galactic evolution from Sd to Sa.

Keywords

Bulge formationGalaxy evolutionN-body simulation
Type
Contributed Papers
Information
Symposium - International Astronomical Union , Volume 153: Galactic Bulges , 1993 , pp. 387 - 390
Copyright
Copyright © Kluwer 1993 

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