Search Publications
The interstellar oxygen-K absorption edge as observed by XMM-Newton. Separation of instrumental and interstellar components
Kaastra, J. S.; de Vries, C. P.; den Herder, J. W. +3 more
High resolution X-ray spectra of the Reflection Grating Spectrometer (RGS) on board the XMM satellite are used to resolve the oxygen K absorption edge. By combining spectra of low and high extinction sources, the observed absorption edge can be split in the true interstellar (ISM) extinction and the instrumental absorption. The detailed ISM edge s…
The central star of the planetary nebula N 66 in the Large Magellanic Cloud: A detailed analysis of its dramatic evolution 1983-2000
Hamann, W. -R.; Gräfener, G.; Ruiz, M. T. +1 more
The central star of the planetary nebula N 66 (alias WS 35, SMP 83 and HV 5967) in the Large Magellanic Cloud enhanced its brightness dramatically in 1993 and 1994. Within the subsequent four years it returned to the previous level. Its spectrum resembles that of a Wolf-Rayet star of the nitrogen sequence (WN4.5). We monitored the object intensive…
AD Leonis : Flares observed by XMM-Newton and Chandra
Raassen, A. J. J.; Mewe, R.; Audard, M. +3 more
The M-dwarf
Fast photospheric flows and magnetic fields in a flaring active region
Meunier, N.; Kosovichev, A.
We present new results from the coordinated observations between the THEMIS telescope (in the multi-line spectropolarimetric mode) and Michelson Doppler Imager (MDI) on SOHO obtained in November 2000 for active region NOAA 9236 which was the source of several X-class flares. The goal of these observations was twofold: to verify MDI measurements of…
High resolution spectroscopy and emission line imaging of DEM L 71 with XMM-Newton
Kaastra, J. S.; Vink, J.; Bleeker, J. A. M. +1 more
The X-ray emission from the supernova remnant DEM L 71 is measured and analysed using the high-resolution cameras and spectrometers on board XMM-Newton. The spectrum from the outer shell is reproduced very well by two plasma components of kTe = 0.3 and 0.8 keV. The abundance value from this shell is consistent with the average LMC value…
High-resolution X-ray spectroscopy of tau Scorpii (B0.2V) with XMM-Newton
Raassen, A. J. J.; Mewe, R.; Güdel, M. +3 more
We report the analysis of the first high-resolution X-ray spectrum of the B0.2V star tau Scorpii obtained with the Reflection Grating Spectrometers (RGS) and the EPIC-MOS CCD spectrometers on board XMM-Newton. The spectrum exhibits bright emission lines of the H- and He-like ions of C, N, O, Ne, Mg, and Si, as well as Fe XVII & Fe XVIII lines.…
JEM-X science analysis software
Hornstrup, A.; Oxborrow, C. A.; Huovelin, J. +9 more
The science analysis of the data from JEM-X on INTEGRAL is performed through a number of levels including corrections, good time selection, imaging and source finding, spectrum and light-curve extraction. These levels consist of individual executables and the running of the complete analysis is controlled by a script where parameters for detailed …
Why hot horizontal branch stars can appear redder than red giants
Recio-Blanco, A.; Momany, Y.; Bedin, L. R. +4 more
In this paper we report on a curious feature in the V, (U-B) color-magnitude diagrams of globular clusters. In our database, we find that a considerable fraction of blue horizontal branch stars, hotter than the instability strip and cooler than the Grundahl et al. (1999) jump (i.e., 6000 <~ Teff(K)<~ 10 000), have (U-B) colors red…
In-flight calibration of the ISGRI camera
Goldoni, P.; Malaguti, G.; David, P. +12 more
ISGRI, the IBIS low energy camera (15 keV-1 MeV) on board INTEGRAL, is the first large CdTe gamma-ray imager in orbit. We present here an overview of the ISGRI in-flight calibrations performed during the first months after launch. We discuss the stability of the camera as well as the CdTe pixels response under cosmic radiation. The energy calibrat…
The central engines of radio-loud quasars
Ho, L. C.; Staubert, R.; Wang, J. -M.
We have assembled a sample of 37 radio-loud quasars that have been imaged with the Hubble Space Telescope in order to investigate their black hole masses, accretion rates, and the structure of their accretion disks. The black hole masses were estimated from the luminosities of the host galaxies, and the accretion powers were extrapolated from the …