Search and study of Ultra-Compact Dwarfs (UCDs) in the Antlia cluster.

JUAN PABLO CASO; LILIA P. BASSINO; TOM RICHTLER; ANALIA V SMITH CASTELLI; FAVIO FAIFER; SERGIO A. CELONE

Sao Jose dos Campos

Workshop; South American Gemini Data Workshop; 2011

Gemini Observatory y National Gemini Offices

The first results in the search for UCDs in the central region of the Antlia cluster are presented, including the confirmation as members of a sample of objects (Caso J. P., PhD Thesis, in prep).The observational material used consists of wide field CCD images (36´ x 36´) from the Cerro Tololo Inter-American Observatory (CTIO, Chile), obtained with the MOSAIC camera in the Washington photometric system; CCD images from Paranal Observatory (ESO), obtained with the camera FORS1 (VLT) of four fields located in the central region of the cluster; and spectra of several fields around NGC3258 and NGC3268, obtained with GMOS (Gemini South, Chile). Two ACS fields on NGC3258 and NGC 3268, observed with the F814 filter, were obtained from the Hubble Space Telescope Data Archive (programme 9427, PI: W. E. Harris).The UCD candidates had been selected from the point sources found in the MOSAIC field, taking into account their colours (C-T1) and magnitudes (T1).Radial velocities were measured from the GMOS spectra, resulting in the confirmation as cluster members of thirteen objects with magnitude in the range corresponding to UCDs and seven in the range of globular clusters (GCs).