Publications of the Astronomical Society of the Pacific
107: 715-729, 1995 August
GALAXIES AND THEIR ENVIRONMENTS
Judith A. Irwin
Department of
Physics, Queen's
University, Kingston, Canada, K7L 3N6
Electronic mail: irwin@astro.queensu.ca
ABSTRACT. Four questions are asked related to galaxies and their
environments in the context of speculation as to which direction the field
may go over the next decade. These are: What is a galaxy? Where does a
galaxy end? Are galaxies open or closed? and How important are
interactions? In the process, these questions touch upon some of the
challenging problems facing us today in extragalactic astronomy, such as
galaxy formation and evolution, the importance of environmental effects,
and the nature and extent of dark matter.
Table of Contents
INTRODUCTION
- WHAT
IS A GALAXY?
- The World of Galaxies
- The Limitations of Conventional Classification
Schemes
- The Physical Properties of Galaxies
- WHERE
DOES A GALAXY END?
- Probing the Formation and Evolution of Disks -
the Extent of the Neutral Hydrogen
- Probing the Unseen Halos - Rotation Curves and
Dark Matter
- ARE
GALAXIES OPEN OR CLOSED?
- Communication with the Environment
- Inflows
- Outflows
- Magnetic Fields
- HOW
IMPORTANT ARE INTERACTIONS?
- Nature versus Nurture
- Interaction-Driven Galaxy Formation
- Subtle Interactions
- SUMMARY
- REFERENCES
