Related papers: Confronting atomic data with Fe L-shell spectra of…
Recent observations of thermally emitting isolated neutron stars revealed spectral features that could be interpreted as radiative transitions of He in a magnetized neutron star atmosphere. We present Hartree-Fock calculations of the…
We use the PHOENIX code package to model the X-ray spectrum of Nova V4743 Sagittarii observed with the LETGS onboard the Chandra satellite on 19 March 2003. To analyze nova atmospheres and related systems with an underlying nuclear burning…
We have been conducting a comprehensive survey of stellar coronae with the XMM-Newton Reflection Grating Spectrometers during the commissioning, calibration, verification, and guaranteed time phases of the mission, accompanied by…
Using the combined spectral and spatial resolving power of the Low Energy Transmission Grating (LETGS) on board Chandra, we obtain separate spectra from the bright central source of NGC 1068 (Primary region), and from a fainter bright spot…
Evaluated nuclear structure and decay data for all nuclei with mass number A=201 (201Os, 201Ir, 201Pt, 201Au, 201Hg, 201Tl, 201Pb, 201Bi, 201Po, 201At, 201Rn, 201Fr, 201Ra) are presented. All available experimental data are compiled and…
We provide improved atomic calculation of wavelengths, oscillator strengths, and autoionization rates relevant to the $2\to 3$ inner-shell transitions of Fe~VI--XVI, the so-called Fe~M-shell unresolved transition array (UTA). A second order…
The best examples of halo nuclei, exotic systems with a diffuse nuclear cloud surrounding a tightly-bound core, are found in the light, neutron-rich region, where the halo neutrons experience only weak binding and a weak, or no, potential…
The solar corona is orders of magnitude hotter than the underlying photosphere, but how the corona attains such high temperatures is still not understood. Soft X-ray (SXR) emission provides important diagnostics for thermal processes in the…
Spatial information from stellar X-ray coronae can be inferred by use of scaling laws from the solar corona. This requires measurement of the physical parameters temperature and density. We concentrate on the newly available density…
We analyze 205 ks of imaging data of the active binary, Capella, obtained with the Chandra High Resolution Camera Imager (HRC-I) to determine whether Capella shows any variability at timescales < 50 ks. We find that a clear signal for…
Absorption lines of H$_2$ and HD molecules observed at high redshift in the line of sight towards quasars are a test ground to search for variation of the proton-to-electron mass ratio $\mu$. For this purpose, results from astronomical…
Neutron and nuclear beta decay correlation coefficients are linearly sensitive to the exotic scalar and tensor interactions that are not included in the Standard Model. The proposed experiment will measure simultaneously 11 neutron…
We have obtained a high spatial resolution X-ray image of the nucleus of NGC 1068 using the High Resolution Camera (HRC-I) on board the Chandra X-ray Observatory, which provides an unprecedented view of the innermost 1 arcsecond radius…
X-ray measurements find systematically lower Fe abundances in the X-ray emitting haloes pervading groups ($kT\lesssim1.7$ keV) than in clusters of galaxies. These results have been difficult to reconcile with theoretical predictions.…
New X-ray observatories (Chandra and XMM-Newton) are providing a wealth of high-resolution X-ray spectra in which hydrogen- and helium-like ions are usually strong features. We present results from a new collisional-radiative plasma code,…
This paper discusses some features of the spectral line profile theory used in the treatment of measured atomic transitions. It is shown that going beyond the established linear approximation for the spectral line contour in the case of its…
The X-ray spectra of late type stars can generally be well fitted by a two temperature component model of the corona. We fnd that the temperature of both components are strong functions of stellar age, although the temperature of the hotter…
We present a first analysis of a high resolution X-ray spectrum of the ionized stellar wind of Vela X-1 during eclipse. The data were obtained with the High Energy Transmission Grating Spectrometer onboard the Chandra X-ray Observatory. The…
While high-resolution cross-correlation spectroscopy (HRCCS) techniques have proven effective at characterizing the atmospheres of transiting and non-transiting hot Jupiters, the limitations of these techniques are not well understood. We…
In previous studies we identified two classes of starless cores, thermally subcritical and supercritical, distinguished by different dynamical behavior and internal structure. Here we study the evolution of the dynamically-unstable,…