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Published online by Cambridge University Press: 07 August 2017
The helium-to-metals enrichment ratio (dY/dZ) and the pregalactic helium abundance (Yp ) are important parameters for the understanding of the galactic chemical evolution, and also as a cosmological test to the Big Bang theory. In this work, we present a new determination of these parameters based on a sample of galactic HII regions, HII galaxies, and planetary nebulae.