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The HSS (Hamburg/SAO survey) constitutes a large collaborative effort between investigators of several countries (Germany, Russia, Ukraine, Israel, France and Spain) to produce a new, large and deep sample of blue compact galaxies in the sky area R.A.=7h20m to 17h40m, DEC=+35 to +50. Emission Line Galaxies (ELGs) are being selected using the plates from the Hamburg Quasar Survey (Ugryumov et al. 1998). So far the number of candidates already detected to be HII galaxies are about 250, for which high S/N spectroscopic studies are needed to select the most unevolved and/or truly young systems.
The snap-shot spectroscopy of the preselected ELG candidates
identified on Hamburg Quasar Survey plates is being carried out
with the Russian 6-m telescope, the 2.2m telescopes of the
German-Spanish Observatory in Calar Alto, the 2.1m telescope of KPNO and
the 1.5m telescope on Observatorio de Sierra Nevada. Using these data a
preliminary classification will be made of the ELGs and selection of the more
interesting galaxies to perform detailed spectroscopy will come out.
One of the main goals of this work is to identify a significant number
of HII galaxies with very low metallicity (Z < 1/10 Z
)
for
chemical abundances studies of these unevolved galaxies. The absence
of galaxies with metallicities close to the one
determined for I Zw 18 (1/50 Z)
is still a puzzling
matter in BCGs research and the different explanations for the lack of
these galaxies in the local Universe constitute a matter of debate.
The understanding of this open question since Zwicky era, 40 years
ago, constitutes one of
the main objectives of our research.