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The primordial helium abundance from updated emissivities
Erik Aver, Keith A. Olive, R. L. Porter +1
Observations of metal-poor extragalactic H II regions allow the determination of the primordial helium abundance, Y_p. The He I emissivities are the foundation of the model of the…
Expanded Iron UTA spectra -- probing the thermal stability limits in AGN clouds
G. J. Ferland, R. Kisielius, F. P. Keenan +5
The Fe unresolved transition array (UTAs) produce prominent features in the 15-17?A wavelength range in the spectra of Active Galactic Nuclei (AGN). Here we present new calculation…
Hydrogen Two-Photon Continuum Emission from the Horseshoe Filament in NGC 1275
R. M. Johnstone, R. E. A. Canning, A. C. Fabian +5
Far ultraviolet emission has been detected from a knot of Halpha emission in the Horseshoe filament, far out in the NGC 1275 nebula. The flux detected relative to the brightness of…
Improved He I Emissivities in the Case B Approximation
R. L. Porter, G. J. Ferland, P. J. Storey +1
We update our prior work on the case B collisional-recombination spectrum of He I to incorporate \textit{ab initio} photoionisation cross-sections. This large set of accurate, self…
Broad and Luminous [OIII] and [NII] in Globular Cluster ULXs
Ryan L. Porter
We consider an accretion-disc origin for the broad and luminous forbidden-line emission observed in ultraluminous X-ray (ULX) sources CXOJ033831.8-352604 and XMMU 122939.7+075333 i…
Implications of infalling Fe II - emitting clouds in active galactic nuclei: anisotropic properties
Gary J. Ferland, Chen Hu, Jian-Min Wang +4
We investigate consequences of the discovery that Fe II emission in quasars, one of the spectroscopic signatures of "Eigenvector 1", may originate in infalling clouds. Eigenvector…