Volume 397, Number 2, January II 2003
|Page(s)||463 - 472|
|Published online||17 December 2002|
The Hamburg/SAO Survey for low metallicity blue compact H II galaxies (HSS–LM)*
I. The first list of 46 strong-lined galaxies
Special Astrophysical Observatory RAS, Nizhnij Arkhyz, Karachai-Circassia 369167, Russia
2 Isaac Newton Institute of Chile, SAO Branch
3 Hamburger Sternwarte, Gojenbergsweg 112, 21029 Hamburg, Germany
4 Max Planck Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
Corresponding author: A. V. Ugryumov, firstname.lastname@example.org
Accepted: 10 September 2002
We present the description and the first results of a new project devoted to the search for extremely metal-deficient blue compact/H ii-galaxies (BCGs) and to the creation of a well selected large BCG sample with strong emission lines. Such galaxies should be suitable for reliable determination of their oxygen abundance through the measurement of the faint  λ 4363 Å line. The goals of the project are two-fold: a) to discover a significant number of new extremely metal-poor galaxies ( 1/20 Z ), and b) to study the metallicity distribution of local BCGs. Selection of candidates for follow-up slit spectroscopy is performed on the database of objective prism spectra of the Hamburg Quasar Survey. The sky region is limited by ° and °. In this paper we present the results of the follow-up spectroscopy conducted with the Russian 6 m telescope. The list of observed candidates contained 52 objects, of which 46 were confirmed as strong-lined BCGs (EW( λ 5007) ≥ 100 Å). The remaining five lower excitation ELGs include three BCGs, and two galaxies classified as SBN (Starburst Nucleus) and DANS (Dwarf Amorphous Nucleus Starburst). One object is identified as a quasar with a strong Lyα emission line near λ 5000 Å (). We provide a list with coordinates, measured radial velocities, B-magnitudes, equivalent widths EW( λ 5007) and EW(Hβ) and for the 46 strong-lined BCGs the derived oxygen abundances 12+(O/H). The abundances range between 7.42 and 8.4 (corresponding to metallicities between 1/30 and 1/3 Z ). The sample contains four galaxies with 1/20 Z , of which three are new discoveries. This demonstrates the high efficiency of the new project to find extremely metal-deficient galaxies. The radial velocities of the strong–lined ELGs range between 500 and 19 000 km s-1 with a median value of ~6400 km s-1. The typical B-magnitudes of the galaxies presented are .
Key words: galaxies: dwarf / galaxies: abundances / galaxies: distances and redshifts / surveys
© ESO, 2003
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.