BCD Galaxies in the Antlia Cluster

SMITH CASTELLI, A. V.; BASSINO, L. ; CELLONE, S.; RICHTLER, T.; DIRSCH, B.; GÓMEZ, M.

Concepción

Otro; Third Advanced Chilean School on Astrophysics: "Insight into Galaxy Evolution from Resolved Stellar Populations"; 2007

Universidad de Concepción, Chile

The Antlia cluster (l=270º, b=20º) is the third nearest galaxy cluster after Virgo and Fornax. Despite its proximity, richness and concentration, it is practically unexplored. We are performing the first CCD photometric study of the galaxy population of this cluster using images taken with MOSAIC at CTIO, in the Washington photometric system. Blue Compact Dwarf (BCD) galaxies are objects with low metal abundances that are forming stars at a very high rate. They present low surface brightness envelopes linked to an old stellar population, which extend several kpc from the central star-forming regions (Caon et al. 2005, Gil de Paz & Madore 2005, and references therein). BCD galaxies also display particular brightness and colour profiles.  The brightness profiles show high central surface brightnesses associated to the young population, that decrease very rapidly with radius due to the presence of the evolved stellar component in the outer regions. Because of this, BCD galaxies also display blue central colour profiles that get redder outwards. In this presentation we show the brightness and colour profiles of five BCD galaxies placed toward the central region of the Antlia cluster. Three of these objects have been previously classified as BCD candidates of Antlia by Ferguson & Sandage (1990), while the other two galaxies are new objects.  We also display colour and filtered maps of these galaxies, in order to show their internal structure.