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Investigating the Chemical Homogeneity of Low-Metallicity Blue CompactDwarf Galaxies Using Integral Field Spectroscopy

Published online by Cambridge University Press:  11 July 2011

M. Koleva ,
Ph. Prugniel ,
I. Vauglin ,
B.L. James ,
Y.G. Tsamis ,
M.J. Barlow ,
M.S. Westmoquette ,
J. Walsh  and
A. Aloisi
B.L. James
Affiliation:
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
Y.G. Tsamis
Affiliation:
Space Telescope European Co-ordinating Facility, ESO, Karl-Schwarzschild Strasse 2, 85748 Garching, Germany
M.J. Barlow
Affiliation:
Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT, UK
M.S. Westmoquette
Affiliation:
Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT, UK
J. Walsh
Affiliation:
Space Telescope European Co-ordinating Facility, ESO, Karl-Schwarzschild Strasse 2, 85748 Garching, Germany
A. Aloisi
Affiliation:
Department of Physics and Astronomy, University College London, Gower Street, London, WC1E 6BT, UK
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Abstract

It has been claimed in the past that in low-metallicity Blue Compact Dwarf (BCDs) galaxies, the N/O value is independent of metallicity (O/H ratio), implying the need to invoke a primary production of nitrogen in intermediate-mass stars, in addition to the secondary nitrogen produced from the CNO cycle in high-mass stars. In order to better understand this controversial issue we undertook an integral field spectroscopic study of the nebular gas within a sample of BCDs previously thought to have anomalously high N/O values. Here we present the results of this study for 3 BCDs: two with anomalous N/O values (Mrk 996 and UM 420) and one with more normal N/O values (UM 462). We describe in detail how we derived the physical conditions (Te, Ne) as a function of position within the galaxy, and as a consequence, how this revealed both revised metallicities and normal N/O ratios and uncovered one of the first clear evidences of nitrogen self-enrichment of an H ii  region from WR stars.

Type
Research Article
Information
European Astronomical Society Publications Series , Volume 48: CRAL-2010 A Universe of Dwarf Galaxies , 2011 , pp. 109 - 114
Copyright
© EAS, EDP Sciences, 2011

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References

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