136 citations · 760 across the 27 of their papers we have counts for
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The Evolution of Helium and Hydrogen Ionization Corrections as HII Regions Age
Ruth Gruenwald, Gary Steigman, Sueli M. Viegas
Helium and hydrogen recombination lines observed in low-metallicity, extragalactic, HII regions provide the data used to infer the primordial helium mass fraction, Y_P. In deriving…
Infrared FeII Emission in Narrow-Line Seyfert 1 Galaxies
A. Rodriguez-Ardila, S. M. Viegas, M. G. Pastoriza +1
We obtained 0.8-2.4 micron spectra at a resolution of 320 km/s of four narrow-line Seyfert 1 galaxies in order to study the near-infrared properties of these objects. We focus on t…
A grid of Composite Models for the Simulation of Starburst Galaxy and HII Region Spectra
M. Contini, S. M. Viegas
A grid of models for starburst spectra is presented and compared with power-law models which represent AGNs. The models are composite, i.e., they account for the radiation from the…
When Photoionization Is Not Enough
Sueli M. Viegas
It is well-known that photoionization is the major mechanism powering nebulae emission-lines. For about 30 years, numerical simulations using photoionization codes have been employ…