Abstract
view Abstract Citations (145) References (62) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Primordial helium, spectrophotometric technique and I Zwicky 18. Davidson, K. ; Kinman, T. D. Abstract Emission-line observations of the dwarf galaxy I Zw 18 were obtained in order to calculate the primordial helium mass fraction Yp. The observations were carried out during five nights in February 1982, using the KPNO 2.1-meter telescope attached to a gold spectrograph and intensified image dissector scanner (IIDS). A mass fraction of 0.122 + or - 0.015 is derived on the basis of the relative line intensities, H-beta fluxes, and equivalent line widths of I Zw 18. It is shown that the estimated standard error of Yp is more realistic than errors predicted in previous studies. The relative line intensities, H-beta fluxes, and equivalent line widths are given in a table. Publication: The Astrophysical Journal Supplement Series Pub Date: July 1985 DOI: 10.1086/191044 Bibcode: 1985ApJS...58..321D Keywords: Abundance; Cosmology; Dwarf Galaxies; Helium; Nuclear Fusion; Spectrophotometry; Data Reduction; Emission Spectra; Error Analysis; Interstellar Extinction; Nebulae; Radiant Flux Density; Spectral Line Width; Astrophysics full text sources ADS | data products SIMBAD (1) NED (1)
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