W. J. Maciel -
Abstract #86
SOME ASPECTS OF THE CHEMICAL EVOLUTION OF 4He IN THE GALAXY: THE He/H RADIAL GRADIENT AND THE Delta Y/Delta Z ENRICHMENT RATIO
W. J. Maciel
IAU Symposium 198, The light elements and their evolution, ed. L. da Silva, M. Spite, J. R. de Medeiros ASP, 204-213 (2000) Two aspects of the chemical evolution of 4He in the Galaxy are considered on the basis of a sample of disk planetary nebulae by the application of corrections due to the contamination of 4He from the progenitor stars. First, the He/H radial gradient is analyzed, and then, the helium to heavy element enrichment ratio is determined for metallicities up to the solar value.
