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We describe the effect that new atomic calculations, including fully-relativistic R-matrix calculations of collisional excitation rates and level-specific dielectronic and radiative recombination rates, have on line ratios from the astrophysically significant ion Ne IX. The new excitation rates systematically change some predicted Ne IX line ratios by 25% at temperatures at or below the temperature of maximum emissivity (4x10^6 K), while the new recombination rates lead to systematic changes at higher temperatures. The new line ratios are shown to agree with observations of Capella and sigma^2 CrB significantly better than older line ratios, showing that 25-30% accuracy in atomic rates is inadequate for high-resolution X-ray observations from existing spectrometers.
The C I 135.58 line is located in the wavelength range of NASAs Interface Region Imagin Spectrograph (IRIS) small explorer mission. We here study the formation and diagnostic potential of this line by means of non local-thermodynamic-equilibrium mode
Cosmic neutrinos above a PeV are produced either within astrophysical sources or when ultra-high energy cosmic rays interact in transit through the cosmic background radiation. Detection of these neutrinos will be essential for understanding cosmic r
We investigate the mechanism to reproduce notable spectral features at the ignition phase of nova explosion observed for a super-Eddington X-ray transient source MAXI J0158$-$744 in the Small Magellanic Cloud. These are a strong Ne IX emission line a
He-like ions produce distinctive series of triplet lines under various astrophysical conditions. However, this emission can be affected by line absorption from Li-like ions in the same medium. We investigate this absorption of He-like triplets and pr
A dramatic increase in the accuracy and statistics of space-borne cosmic ray (CR) measurements has yielded several breakthroughs over the last several years. The most puzzling is the rise in the positron fraction above ~10 GeV over the predictions of