NOAO >   Observing Info >   Approved Programs >   2002B-0149

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Proposal Information for 2002B-0149


PI: Trinh Xuan Thuan, University of Virginia, txt@virginia.edu
Address: P.O.Box 3818, University Station, Charlottesville, VA 22903, USA

CoI: Yuri Izotov, Main Astronomical Observ., Kyiv, Ukraine

Title: The dY/dZ slope from a new sample of metal-deficient blue compact dwarf galaxies from the SLOAN survey

Abstract: We propose to obtain follow-up high signal-to-noise ratio spectrophotometric observations for a new sample of ~ 35 metal- deficient blue compact dwarf (BCD) galaxies, selected out of a total list of ~ 300 BCDs with [O III] 4363 emission, compiled from the first public release of the Sloan Digital Sky Survey spectra. Our main aim is the determination of an accurate dY/dZ slope which measures the change of the ^4He mass fraction Y relative to the mass fraction of heavy elements Z, and which not only constrains the primordial helium abundance, but also stellar and chemical evolution models of dwarf galaxies. The slope dY/dZ can be obtained with a very good precision using the Sloan BCDs because of their relatively large range of metallicities (Z_\odot/20 - Z_\odot/3). Secondary aims include the determination of the N, O, Ne, S, Ar and Fe abundances to constrain low-metallicity stellar nucleosynthesis models, and the study of Wolf- Rayet BCDs which constrains stellar evolutionary models of massive stars.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



NOAO >   Observing Info >   Approved Programs >   2002B-0149

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