Search Publications
The broad-band spectrum of Cyg X-2 with INTEGRAL
Stella, L.; van der Klis, M.; Lewin, W. H. G. +7 more
We study the broad band (3-100 keV) spectrum of Cygnus X-2 with INTEGRAL. We find that the spectrum is well fitted by a Comptonized component with a seed-photons temperature of ∼ 1 keV, an electron temperature of ∼ 3 keV and an optical depth τ ∼ 8. Assuming spherical geometry, the radius of the seed-photons emitting region is ∼ 17 km. The source s…
The Type Ia Supernova rate in the local Universe
Strigari, Louis E.
Current measurements of the Type Ia Supernova (SNIa) rate, as determined by standard astronomical methods, are in reasonable agreement with measurements of the cosmic star formation rate combined with simple models for SNIa progenitors. However, systematic uncertainties still undermine a precise determination of the SNIa rate. Recent models of the…
The Precataclysmic Binary HS 1136+6646 May Have a Companion
Holberg, J. B.; Sing, D. K.; Liebert, James +1 more
Because of the similarity of the primary star of HS 1136+6646 to the planetary nebula central star BE Ursae Majoris, we performed wide-field imaging of the former with an Hα filter. No nebulosity was detected. On the other hand, the point-spread function of the star appears extended. A partially resolved red component is detected in an image from …
Chemical abundances in AGN : X-ray/UV campaign on Mrk 279 .
Arav, Nahum
We present the first reliable chemical abundances determination in an AGN outflow. The abundances are extracted from the deep and simultaneous FUSE and HST/STIS observations of Mrk 279. This data-set is exceptional for it's high signal-to-noise, unblended doublet troughs and little galactic absorption contamination. These attributes allow us to so…
The HIPPARCOS Mission: a New Era for Variable Star Astronomy
Eyer, L.; Grenon, M.
Initially planned as a pure astrometric mission, Hipparcos was optimized to produce the highest achievable photometric accuracy in the Hp broad-band and in the Tycho BT and VT bands. A complex calibration process allowed to cope with the rapid change of the optics and to fix the magnitude scale to better than 0.001 magnitude throughout the mission…
Space Physics: Breaking through the lines
Paschmann, Götz
Magnetic field lines are known to reorganize themselves in plasmas, converting magnetic to particle energy. Evidence harvested from the solar wind implies that the scale of the effect is larger than was thought.
Dust scattering X-ray expanding rings around gamma-ray bursts
Tiengo, A.; Mereghetti, S.; Vianello, G.
Scattering by dust grains in our Galaxy can produce X-ray halos, visible as expanding rings, around GRBs. This has been observed in three GRBs to date, allowing to derive accurate distances for the dust clouds as well as some constraints on the prompt GRB X-ray emission that was not directly observed. We developed a new analysis method to study du…
Energetic electron signatures in an active magnetotail plasma sheet
Grande, M.; Davies, J. A.; Fazakerley, A. N. +10 more
Particles with energies of tens to hundreds of keV provide a powerful diagnostic of the acceleration processes that characterise the Earth's magnetosphere, in particular the highly dynamic nightside plasma sheet. Such energetic particles can be detected by the RAPID experiment, onboard the quartet of Cluster spacecraft. We present results from the…
Ultraviolet Studies Of Interacting Binaries
Shore, Steven N.; Long, Knox S.; Marsh, Thomas R. +4 more
Interacting Binaries consist of a variety of stellar objects in different stages of evolution and those containing accreting compact objects still represent a major challenge to our understanding of not only close binary evolution but also of the chemical evolution of the Galaxy. These end-points of binary star evolution are ideal laboratories for…
Cataclysmic Variables Observed with INTEGRAL
Simon, Vojtech; Hudec, René; Munz, Filip +1 more
We discuss selected results of observations of cataclysmic variables (CVs) and related objects by the instruments IBIS (far X-ray and gamma-ray imager) and OMC (Optical Monitoring Camera) onboard INTEGRAL. We concentrate on the analysis of the time behaviour of the intermediate polar (IP) V1223 Sgr, seen simultaneously by IBIS and OMC in a state w…