New southern blue compact dwarf galaxies in the 2dF Galaxy redshift survey
Institut für Astrophysik, Friedrich-Hund-Platz 1, 37077 Göttingen, Germany e-mail: firstname.lastname@example.org
2 Main Astronomical Observatory, Ukrainian National Academy of Sciences, 27 Zabolotnoho str., Kyiv 03680, Ukraine
3 University of California, 1156 High St., Santa Cruz, CA 95064, USA
4 Astronomy Department, University of Virginia, Charlottesville, VA 22903, USA
Accepted: 12 May 2006
Aims.Aiming to find new extremely metal-deficient star-forming galaxies we extracted from the Two-Degree Field Galaxy Redshift Survey (2dFGRS) 100 K Data Release 14 emission-line galaxies with relatively strong [O iii] λ4363 emission.
Methods.Spectroscopic and photometric studies of this sample and, in addition, of 7 Tololo and 2 UM galaxies were performed on the basis of observations with the ESO 3.6 m telescope.
Results.All sample galaxies qualify with respect to their photometric and spectroscopic properties as blue compact dwarf (BCD) galaxies. Additionally, they show a good overlap with a comparison sample of ~100 well-studied emission-line galaxies on the vs. log(Ne/O), log(Ar/O) and log(Fe/O) planes. From the analysis of the 2dFGRS subsample we report the discovery of two new extremely metal-deficient BCDs with an oxygen abundance ≤ 7.6 and of another seven galaxies with 7.8. Furthermore, we confirm previous oxygen abundance determinations for the BCDs Tol 1304-353, Tol 2146-391, UM 559 and UM 570 to be ≤ 7.8.
Key words: galaxies: starburst / galaxies: abundances / galaxies: fundamental parameters / galaxies: structure
© ESO, 2006