CfA Colloquium: November 21, 2002

Speaker: Heather Morrison (Case Western)

Title: Star Streams in the Milky Way -- Fragments of its History

Abstract: The last 10-20 years has seen a profound shift in views of how the Galaxy's halo formed. The idea of a monolithic early collapse of a single system (Eggen, Lynden-Bell and Sandage 1962) has been challenged by observations at high redshift and by cosmological models of structure formation. These findings imply that we should see clear evidence of hierarchical formation processes in nearby galaxies. Recent studies of our Galaxy, made possible by large-scale CCD surveys such as the Sloan Digital Sky Survey (SDSS), have begun to reveal evidence of substructure in the outer halo. I will review evidence for tidal streams associated with known Milky Way satellites and for star streams whose progenitors are still unknown, and then discuss ways that we can use the star streams to study the dark matter halo of the Milky Way and the structure of the progenitor galaxies.

Reference for students:
Dohm-Palmer et al, ApJ 555, L37, 2001.