Bibcode
Gallego, J.; Zamorano, J.; Rego, M.; Vitores, A.
Bibliographical reference
In NASA. Ames Research Center, The Evolution of Galaxies and Their Environment p 295-296 (SEE N93-26706 10-90)
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1
1993
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Description
We are carrying out a long-term project with the main purposes of
finding and analyzing low metallicity galaxies. A very small number of
very low metallicity galaxies is known up to now. However these ojbects
are particularly interesting since they are excellent candidates to
'young galaxies' in evolutionary sense as POX186 (Kunth, Maurogordato
& Vigroux, 1988). Since the interstellar matter in these objects is
only weakly contaminated by stellar evolution, their study could provide
valuable information about the primordial helium abundance and therefore
it could place constraints on the different Big-Bang models. The
instrumental set up of our survey is an objective-prism used with the
Schmidt telescope at Calar Alto Observatory. By using hypersensitized
IIIaF emulsion and RG630 filter low resolution spectra in the H alpha
region of objects in a wide field is obtained (Rego et al. 1989,
Zamorano et al. 1990). Surveys carried out in the past two decades at
optical blue wavelengths have also produced large samples of
emission-line galaxies (ELGs), for example MacAlpine & Willians 1981
and reference therein, Wasilewski 1983, Salzer and MacAlpine 1988, or
Smith et al. 1976. Relying primarily on objective-prism plates taken in
the blue, these surveys have found over 3000 blue/emission-line galaxies
so far. A significant number of star-forming galaxies are missed by
optical surveys in the blue because of their low-excitation spectra
(MacAlpine and Willians 1981, Markarian et al. 1981 and references
therein) or their low metallicity (Kunth and Sargent, 1986).