Search Publications
Kinetic equilibrium of iron in the atmospheres of cool stars. III. The ionization equilibrium of selected reference stars
Korn, A. J.; Gehren, T.; Shi, J.
Non-LTE line formation calculations of Fe I are performed for a small number of reference stars to investigate and quantify the efficiency of neutral hydrogen collisions. Using the atomic model that was described in previous publications, the final discrimination with respect to hydrogen collisions is based on the condition that the surface gravit…
Formation scenarios for the young stellar associations between galactic longitudes l = 280degr - 360degr
Dias, W. S.; Lépine, J. R. D.; Sartori, M. J.
We investigate the spatial distribution, the space velocities and age distribution of the pre-main sequence (PMS) stars belonging to Ophiuchus, Lupus and Chamaeleon star-forming regions (SFRs), and of the young early-type star members of the Scorpius-Centaurus OB association. These young stellar associations extend over the galactic longitude rang…
Discovery of a magnetic field in the Slowly Pulsating B star zeta Cassiopeiae
Frémat, Y.; Neiner, C.; Wiersema, K. +5 more
The INTEGRAL IBIS/ISGRI System Point Spread Function and Source Location Accuracy
Goldoni, P.; Rodriguez, J.; Foschini, L. +5 more
The imager on board INTEGRAL (IBIS) presently provides the most detailed sky images ever obtained at energies above 30 keV. The telescope is based on a coded aperture imaging system which allows to obtain sky images in a large field of view (29deg x 29deg) with an angular resolution of 12'. The System Point Spread Function of…
XMM-NEWTON High resolution spectroscopy of NGC 5548
Kaastra, J. S.; Steenbrugge, K. C.; de Vries, C. P. +1 more
We analyze a 137 ks exposure X-ray spectrum of the Seyfert 1 galaxy NGC 5548 obtained with the XMM-Newton Reflection Grating Spectrometer. Due to the long exposure time, the spectrum is of higher statistical quality than the previous observations of this AGN. Therefore, we detect for the first time in NGC 5548 inner-shell transitions from O Iii to…
ISO spectroscopy of star formation and active nuclei in the luminous infrared galaxy NGC 6240
Lutz, D.; Genzel, R.; Sturm, E. +4 more
We present Infrared Space Observatory mid- and far-infrared spectroscopy of the merging galaxy
A study of coronal abundances in RS CVn binaries%
Raassen, A. J. J.; Mewe, R.; Audard, M. +2 more
We present XMM-Newton data of several RS CVn binary systems. High-resolution X-ray spectra obtained with the Reflection Grating Spectrometers have been interpreted simultaneously with the European Photon Imaging Camera spectra. Highly active stars show a depletion of elements with a low first ionization potential (FIP) relative to high-FIP element…
A self-consistent treatment of radiation in coronal loop modelling
Mason, H. E.; Bradshaw, S. J.
We perform a hydrodynamic simulation of a cooling coronal loop and calculate the time-dependent ion populations of the most abundant elements of the solar atmosphere at each time-step. We couple the time-dependent ion balance equations to the hydrodynamic equations in order to treat the energy loss through radiation in a self-consistent way by all…
Entropy scaling in galaxy clusters: Insights from an XMM-Newton observation of the poor cluster A1983
Arnaud, M.; Pratt, G. W.
An XMM-Newton observation of the cool (kT =2.1 keV ) cluster A1983, at z=0.044, is presented. Gas density and temperature profiles are calculated over the radial range up to 500 h50-1 kpc, corresponding to ~ 0.35 rv . The outer regions of the surface brightness profile are well described with a beta -model with beta =0.74, bu…
3D dynamical evolution of the interstellar gas in the Gould Belt
Grenier, I. A.; Perrot, C. A.
The dynamical evolution of the Gould Belt has been modelled in 3D and compared to the spatial and velocity distributions of all HI and H2 clouds found within a few hundred parsecs from the Sun and to the Hipparcos distances of the nearby OB associations. The model describes the expansion of a shock wave that sweeps momentum from the amb…