A. V. Ugryumov

On the metallicities of UM 133, UM 283 and UM 382

The study of group properties of the extremely metal-deficient gas-rich local dwarfs is very promising for the understanding the galaxy formation process at high redshifts. About 20 such objects have been picked up from the literature in the recent review by Kunth & Ostlin(2000). However part of these galaxies got low metallicity as a result of earlier observations, and can have rather large uncertainties in their cited element abundances. Before to perform the detailed studies of such galaxies as of some extreme group, it is useful to revise their metallicities. We present the results of the SAO 6m telescope spectrophotometry of two Blue Compact Galaxies (BCG) reported from earlier studies as very metal-poor objects. Well measured [O III] line 4363 A allows to deduce the temperature in HII regions and get reliable abundances of chemical elements. For UM 133 we derive 12+log(O/H) = 7.63+/-0.02, coincident with the published value. UM 382, according to our data, is significantly more metal-rich: its 12+log(O/H) = 7.82+/-0.03 in comparison to the published value 7.45. The third galaxy, UM 283 seems have got its very low 12+log(O/H) = 7.59 due to a misprint. We used its published emission line intensities and derived instead the value of 7.95. Thus the latter two galaxies should NOT be considered as the extremely metal-poor BCGs.

The Hamburg/SAO Survey for low metallicity blue compact H II galaxies (HSS–LM) - I. The first list of 46 strong-lined galaxies

We present the description and the first resultsof a new project devoted to the search for extremely metal- deficient blue compact/H -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 (O ) λ4363 A line. The goals of the project are two-fold: a) to discover a significant number of new extremely metal- poor galaxies (Z 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 δ ≥ 0 ◦ and b II ≤− 30 ◦ . In this paper we present the results of the follow-up spectroscopy conducted with the Russian 6m telescope. The list of observed candidates contained 52 objects, of which 46 were confirmed as strong-lined BCGs (EW((O ) λ5007) ≥ 100 A). 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 λ5000 A (z ∼ 3). We provide a list with coordinates, measured radial velocities, B-magnitudes, equiv- alent widths EW((O ) λ5007) and EW(Hβ) and for the 46 strong-lined BCGs the derived oxygen abundances 12+log(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 Z 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 19000 kms −1 with a median value of ∼6400 kms −1 . The typical B-magnitudes of the galaxies presented are 17. m 0−18. m 0.

The metallicities of UM 151, UM 408 and A 1228+12 revisited

We present the results of new spectrophotometry and heavy element abundance determinations for 3 dwarf galaxies UM 151, UM 408 and A 1228+12 (RMB 132). These galaxies have been claimed in the literature to have very low metallicities, corresponding to log(O=H) + 12 7.65, that are in the metallicity range of some candidate local young galaxies. We present higher S/N data for these three galaxies. UM 151 and UM 408 have sig- nicantly larger metallicities: log(O=H)+12 = 8.5 and 7.93, respectively. For A 1228+12 our new log(O= H) +1 2 = 7.73 is close to that recalculated from earlier data (7.68). Thus, the rederived metallicities allow us to remove these objects from the list of galaxies with Z 1=20 Z.

The Hamburg/SAO survey for emission-line galaxies

We present the second part of the Hamburg/SAO Survey for Emission-Line Galaxies (HSS therein, SAO – Special Astrophysical Observatory, Russia) which is based on the digitized objective-prism photoplates database of the Hamburg Quasar Survey (HQS). The main goal of the project is the search for emission-line galaxies (ELG) in order to create a new deep sample of blue compact/Hii galaxies (BCG) in a large sky area. Another important goal of this work is to search for new extremely low-metallicity galaxies. In this paper we present new results of spectroscopy obtained with the 6 m Russian telescope. The main ELG candidate selection criteria applied are blue or flat enough continuum (near λ4000 A) and the presence of strong or moderate [Oiii]λλ4959, 5007 A emission lines recognized on digitized prism spectra of galaxies with the survey estimated B-magnitudes in the range 16 − 19. 5. No other criteria were applied. The spectroscopy resulted in detection and quantitative spectral classification of 134 emission-line objects. For 121 of them the redshifts are determined for the first time. For 13 ELGs known before emission line ratios are presented at first time. 108 of 134 emission-line objects are classified as BCG/Hii galaxies and probable BCGs, 6 – as QSOs, 1 – as Seyfert galaxy, 1 – as super-association in a dwarf spiral galaxy, 2 – as probable LINERs, 14 are low excitation objects – either of starburst nuclei (SBN), or dwarf amorphous nuclei Send offprint requests to: sap@sao.ru ? Deceased September 22, 1996. 1 Tables 2 to 6 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html. Figures A1 to A13 will be made available only in the electronic version of the journal. Appendix A is only available at http://www.edpsciences.com starburst galaxy (DANS) type, and 2 – nonclassified. 23 galaxies did not show significant emission lines. The five most metal-deficient BCGs discovered have oxygen abundances log(O/H)+12 in the range 7.4 to 7.7, similar to the most metal-deficient BCGs known before.We present the fourth list with results of the Hamburg/SAO Survey for Emission-Line Galaxies (HSS hereafter, SAO - Special Astrophysical Observatory, Russia). The list is a result of the follow-up spectroscopy conducted with the 6m SAO RAS telescope in 1998, 1999 and 2000. The data of this snap-shot spectroscopy survey confirmed 127 emission-line objects out of 176 observed candidates and allowed their quantitative spectral classification. We could classify 76 emission-line objects as BCG/HII galaxies or probable BCGs, 8 - as QSOs, 2 - as Seyfert galaxies, 2 - as super-associations in a subluminous spiral and an irregular galaxy, and 37 as low-excitation objects - either starburst nuclei (SBN), or dwarf amorphous nuclei starburst galaxies (DANS). We could not classify 2 ELGs. Furthermore, for 5 galaxies we did not detect any significant emission lines. For 91 emission-line galaxies, the redshifts and/or line intensities are determined for the first time. Of the remaining 28 previously known ELGs we give either improved data on the line intensities or some independent measurements. The candidates were taken from three different samples selected by different criteria. Among our first priority candidates we achieved a detection rate of emission-line objects (ELGs + QSOs) of 68%, among which 51% are BCGs. Observations of a random selected sample among our second priority candidates showed that only ~10% are BCGs. We found that the confirmed BCGs have usually a blue colour ((B-R)<1.0) and a non-stellar appearance in the APM database. Our third sample is comprised of second priority candidates fulfilling these criteria derived from the APM. Follow-up spectroscopy of a small subsample indicates that the expected detection rate for BCGs is ~40%.