To be published in Planets, Stars, and Stellar Systems, Vol. 6, Series Editor T. D. Oswalt, Volume editor W. C. Keel, Springer Reference, 2011
astro-ph/1102.0550

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GALAXY MORPHOLOGY

Ronald J. Buta


Department of Physics and Astronomy, University of Alabama, Box 870324, Tuscaloosa, AL 35487


Abstract: Galaxy morphology is a product of how galaxies formed, how they interacted with their environment, how they were influenced by internal perturbations, AGN, and dark matter, and of their varied star formation histories. This article reviews the phenomenology of galaxy morphology and classification with a view to delineating as many types as possible and how they relate to physical interpretations. The old classification systems are refined, and new types introduced, as the explosion in available morphological data has modified our views on the structure and evolution of galaxies.


Subject headings: galaxies: spiral; galaxies: elliptical; galaxies: S0s; galaxies: structure; galaxies: high redshift; galaxies: classification; galaxies: peculiar; galaxies: dwarfs; galaxies: clusters; galaxies: active; galaxies: isolated; galaxies: Galaxy Zoo project


Index terms: Hubble-Sandage-de Vaucouleurs classification; spiral galaxies; elliptical galaxies; S0 galaxies; irregular galaxies; resonance ring galaxies; outer rings; inner rings; nuclear rings; secondary bars; nuclear bars; pseudorings; grand design spirals; flocculent spirals; merger morphologies; tidal tails; collisional ring galaxies; polar ring galaxies; barred galaxies; lens galaxies; spiral arm classes; counter-winding spiral galaxies; anemic spiral galaxies; spiral arm multiplicity; dust lanes; pseudobulges; classical bulges; dust-lane elliptical galaxies; shell/ripple galaxies; ultra-luminous infrared galaxies; bar ansae; brightest cluster members; low surface brightness galaxies; dwarf galaxies; dwarf spiral galaxies; dwarf spheroidal galaxies; Galaxy Zoo project; isolated galaxies; blue compact dwarf galaxies; star-forming galaxy morphologies; warped disks; stellar mass morphology; luminosity classes; boxy ellipticals; disky ellipticals; late-type galaxies; early-type galaxies; Magellanic barred galaxies; color galaxy morphology; atomic and molecular gas galaxy morphology


Table of Contents

INTRODUCTION

OVERVIEW

GALAXY CLASSIFICATION

A CONTINUUM OF GALACTIC FORMS

GALAXY TYPES: STAGE, FAMILY, AND VARIETY
Elliptical and Spheroidal Galaxies
S0 and Spiral Galaxies
Irregular Galaxies

OTHER DIMENSIONS TO GALAXY MORPHOLOGY
Outer Rings and Pseudorings
Inner and Outer Lenses
Nuclear Rings and Bars
Spiral Arm Morphologies
Luminosity Effects

THE MORPHOLOGY OF GALACTIC BARS AND OVALS

DUST MORPHOLOGIES

THE MORPHOLOGIES OF GALACTIC BULGES

EFFECTS OF INTERACTIONS AND MERGERS
Normal versus Catastrophic Rings
Environmental Effects on Star-Forming Disks
Interacting and Peculiar Galaxies
Tidal Tails, Arms, and Bridges
Dust-Lane Ellipticals
Shell/Ripple Galaxies
Ultra-Luminous Infrared Galaxies
Warps
The Morphology of Active Galaxies
The Morphology of Brightest Cluster Members

STAR FORMATION MORPHOLOGIES
H{alpha} Imaging
Ultraviolet Imaging
Atomic and Molecular Gas Morphology

INFRARED OBSERVATIONS: GALACTIC STELLAR MASS MORPHOLOGY

INTERMEDIATE AND HIGH REDSHIFT GALAXY MORPHOLOGY

GIANT LOW SURFACE BRIGHTNESS GALAXIES

GALAXY MORPHOLOGY IN COLOR
Normal Galaxies
Dwarf Galaxies
dE, dS0, BCD, and cE Galaxies
Local Group Dwarf Spheroidals and Irregulars
Dwarf Spirals
Galaxy Zoo Project
Isolated Galaxies
Deep Field Color Imaging

LARGE-SCALE AUTOMATED GALAXY CLASSIFICATION

THE STATUS AND FUTURE OF MORPHOLOGICAL STUDIES

REFERENCES

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