EDP Sciences
Free access
Issue
A&A
Volume 394, Number 1, October IV 2002
Page(s) L15 - L18
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:20021294


A&A 394, L15-L18 (2002)
DOI: 10.1051/0004-6361:20021294

Letter

A metallicity-flattening relation for dwarf elliptical galaxies

F. D. Barazza and B. Binggeli

Astronomisches Institut, Universität Basel, Venusstrasse 7, 4102 Binningen, Switzerland

(Received 2 September 2002 / Accepted 5 September 2002)

Abstract
It is shown that bright cluster dwarf ellipticals follow a relation between metallicity and apparent flattening. Rounder dwarfs tend to be more metal-rich. The evidence is based on colour as well as spectroscopic line-strength data from the literature. The large scatter of dEs around the mean metallicity-luminosity relation, usually ascribed to large observational errors, turns out to be an ellipticity effect. In the magnitude range $-14 \ga M_B \ga -18$ the metallicity of dEs depends more strongly on ellipticity than luminosity. A possible explanation is that galaxies with masses around $10^{9}~M_{\odot}$ suffered a partial blowout of metal-enriched gas along their minor axis, rendering ellipticity a critical parameter for metallicity (De Young & Heckman 1994).


Key words: galaxies: general -- galaxies: fundamental parameters -- galaxies: elliptical -- galaxies: dwarf -- galaxies: evolution

Offprint request: F. D. Barazza, barazza@astro.unibas.ch

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