Astronomy and Astrophysics Review 1994, 6, 67-122


Dwarf Elliptical Galaxies

Henry C. Ferguson 1


Space Telescope Science Institute 2
3700 San Martin Drive, Baltimore, MD 21218 USA
ferguson@stsci.edu

Bruno Binggeli


Astronomisches Institut der Universität Basel
Venusstrasse 7, CH-4102 Binningen, Switzerland
binggeli2@ubaclu.unibas.ch


ABSTRACT. Dwarf elliptical (dE) galaxies, with blue absolute magnitudes typically fainter than MB = -16, are the most numerous type of galaxy in the nearby universe. Tremendous advances have been made over the past several years in delineating the properties of both Local Group satellite dE's and the large dE populations of nearby clusters. We review some of these advances, with particular attention to how well currently available data can constrain

  1. models for the formation of dE's,
  2. the physical and evolutionary connections between different types of galaxies (nucleated and nonnucleated dE's, compact E's, irregulars, and blue compact dwarfs) that overlap in the same portion of the mass-spectrum of galaxies,
  3. the contribution of dE's to the galaxy luminosity functions in clusters and the field,
  4. the star-forming histories of dE's and their possible contribution to faint galaxy counts, and
  5. the clustering properties of dE's.

In addressing these issues, we highlight the extent to which selection effects temper these constraints, and outline areas where new data would be particularly valuable.


Key words: Galaxies: general - Galaxies: luminosity function, mass function - Galaxies: evolution - Galaxies: structure - Galaxies: stellar content - Galaxies: fundamental parameters


Table of Contents

purpledotINTRODUCTION
purpledotWhat is a dE galaxy ?
purpledotA brief history
purpledotTheory

purpledotSTRUCTURE
purpledotMorphological distinction
purpledotPhotometric properties

purpledotKINEMATICS AND DYNAMICS
purpledotThe fundamental plane
purpledot(Non-) rotational support
purpledotLocal dE's and dark matter

purpledotSTELLAR CONTENT
purpledotThe local dwarfs
purpledotColors and spectra of cluster dE's
purpledotCorrelations between stellar populations and structure

purpledotLUMINOSITY FUNCTIONS
purpledotSelection effects
purpledotClusters vs. field

purpledotSPATIAL DISTRIBUTION AND CLUSTERING PROPERTIES
purpledotDistribution within clusters
purpledotDwarf companions in the field

purpledotEVOLUTIONARY SCENARIOS
purpledotGravitational collapse
purpledotBiasing
purpledotCooling
purpledotSuppression of star formation: external agents
purpledotSuppression of star formation: internal agents
purpledotSecular evolutoin of irregulars to dE's
purpledotdE's as debris

purpledotAPPLICATIONS TO COSMOLOGY
purpledotDwarf ellipticals as distance indicators
purpledotContribution to faint galaxy counts

purpledotCONCLUSIONS

purpledotREFERENCES


1 Hubble Fellow
2 Operated by the Association of Universities for Research in Astronomy, Inc. under contract with the National Aeronautics and Space Administration

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