S. Nahar

Publications282
h-index26
Citations2,455
Highly Influential Citations144
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ANISOTROPIC LINE EMISSION AND THE GEOMETRY OF THE BROAD-LINE REGION IN ACTIVE GALACTIC NUCLEI
The rapid response of the broad emission lines to continuum variations in the Seyfert galaxy NGC 5548 implies that line-emitting regions are very close to the continuum source. As described in this…
A higher-than-predicted measurement of iron opacity at solar interior temperatures
TLDR
Measurements of wavelength-resolved iron opacity at electron temperatures and electron densities at the solar radiation/convection zone boundary show that wavelength-dependent opacity is 30–400 per cent higher than predicted, which represents roughly half the change in the mean opacity needed to resolve the solar discrepancy.
Electron-Ion Recombination Rate Coefficients, Photoionization Cross Sections, and Ionization Fractions for Astrophysically Abundant Elements. I. Carbon and Nitrogen
We present a comprehensive and self-consistent set of new atomic data for ionization balance in radi- atively and collisionally ionized astrophysical plasmas. Complex resonant phenomena resulting in…
X-ray absorption via Kα resonance complexes in oxygen ions
The Kα resonance complexes in oxygen ions O I‐O VI are theoretically computed, and resonance oscillator strengths and wavelengths are presented. The highly resolved photoionization cross-sections,…
Atomic Astrophysics and Spectroscopy
1. Introduction 2. Atomic structure 3. Atomic processes 4. Radiative transitions 5. Electron-ion collisions 6. Photoionization 7. Electron-ion recombination 8. Multi-wavelength emission lines 9.…
Electron-Ion Recombination Rate Coefficients For Si I, Si II, S II, S III, C II, and C-like Ions C I, N II, O III, F IV, Ne V, Na VI, Mg VII, Al VIII, Si IX, and S XI
Improved collision strengths and line ratios for forbidden [O III] far-infrared and optical lines
Far-infrared and optical [O III] lines are useful temeprature-density diagnostics of nebular as well as dust obscured astrophysical sources. Fine structure transitions among the ground state levels…
Atomic data from the Iron Project. XVII. Radiative transition probabilities for dipole allowed and forbidden transitions in Fe III
Transition probabilities are obtained for both the dipole allowed (E1) ne structure transitions and the forbidden electric quadrupole and magnetic dipole (E2, M1) transitions in Fe III. For the E1…
Electron-Ion Recombination Rate Coefficients and Photoionization Cross Sections for Astrophysically Abundant Elements. III. Si-Sequence Ions: Si I, S III, Ar V, Ca VII, and Fe XIII
Photoionization cross sections, σPI, and electron-ion recombination rate coefficients, αR, for silicon-like ions are calculated. Calculations are carried out in the close coupling approximation using…
A collection of model stellar spectra for spectral types B to early-M
Context. Models of stellar spectra are necessary for interpreting light from individual stars, planets, integrated stellar populations, nebulae, and the interstellar medium. Aims. We provide a…
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