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Very metal poor Classical Cepheids: variables in IZw18

Published online by Cambridge University Press:  01 December 2006

G. Fiorentino ,
M. Marconi ,
G. Clementini ,
I. Musella ,
A. Aloisi ,
F. Annibali ,
R. A. Contreras  and
M. Tosi
G. Fiorentino
Affiliation:
INAF-OABo, via Ranzani 1, 40137, Bologna, Italia email: giuliana.fiorentino@oabo.inaf.it
M. Marconi
Affiliation:
INAF-OAC, via Moiariello 16, 80131, Napoli, Italia
G. Clementini
Affiliation:
INAF-OABo, via Ranzani 1, 40137, Bologna, Italia email: giuliana.fiorentino@oabo.inaf.it
I. Musella
Affiliation:
INAF-OAC, via Moiariello 16, 80131, Napoli, Italia
A. Aloisi
Affiliation:
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218
F. Annibali
Affiliation:
Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218
R. A. Contreras
Affiliation:
INAF-OABo, via Ranzani 1, 40137, Bologna, Italia email: giuliana.fiorentino@oabo.inaf.it
M. Tosi
Affiliation:
INAF-OABo, via Ranzani 1, 40137, Bologna, Italia email: giuliana.fiorentino@oabo.inaf.it
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Abstract

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In the framework of an ongoing ACS@HST project (HST program #10586, PI: Aloisi) we have obtained deep multi-color imaging of the very metal-poor Blue Compact Dwarf galaxy IZw18. The data were acquired in time-series fashion to allow the identification of Classical Cepheids (CCs). The main aim of this project is to constrain both the distance and the Star Formation History of the galaxy. However, as a byproduct these data also provide new insights into the properties of CCs at very low metallicities. We have identified 24 candidate CCs in IZw18. New theoretical pulsation models of CCs specifically for the low metallicity of this primordial galaxy (Z=0.0004, Y=0.24) have been computed to interpret our results.

Keywords

stars: variables: Cepheids
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 2 , Symposium S241: Stellar Populations as Building Blocks of Galaxies , December 2006 , pp. 341 - 342
Copyright
Copyright © International Astronomical Union 2007

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