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The Formation Chronology of Local Group Spiral Galaxies
Published online by Cambridge University Press: 03 August 2017
Abstract
The ‘Second Parameter Effect’ (2ndPE) has long been recognized as an important probe into the formation of spiral galaxies. The concept that the horizontal branch morphologies of globular clusters are primarily affected by metal abundance in the inner halo (RGC<8 kpc) of the Galaxy but require an additional parameter (probably cluster age) to explain their behavior in the outer halo (RGC > 8 kpc), suggests that the former experienced a rapid monotonic collapse while the latter underwent a slower chaotic formation scenario. As such, in the Milky Way, the so-called second parameter boundary is located at 8 kpc. We find that, in the other Local Group spirals — M31 and M33 — this boundary lies at ∼40 kpc and ∼0 kpc, respectively. We therefore speculate that the boundary delimiting rapid monotonic halo collapse from the chaotic accretion of dwarf galaxy fragments is inversely related to the mass of the spiral galaxy.
- Type
- Part 1. The Star Clusters of Local Group Galaxies
- Information
- Symposium - International Astronomical Union , Volume 207: Extragalactic Star Clusters , 2002 , pp. 73 - 82
- Copyright
- Copyright © Astronomical Society of the Pacific 2002