Search Publications
Spectral energy distribution of the metagalactic ionizing radiation field from QSO absorption spectra
Levshakov, S. A.; Agafonova, I. I.; Centurión, M. +1 more
A computational procedure is presented to estimate the spectral shape of the ionizing background between 1 and 10 Ryd by analyzing optically thin absorption systems in the spectra of high redshift quasars. The procedure is based on the response surface methodology from the theory of experimental design. The shape of the recovered UV background at …
The enigmatic B[e]-star Henize 2-90: the non-spherical mass loss history from an analysis of forbidden lines
Borges Fernandes, M.; Kraus, M.; Lamers, H. J. G. L. M. +1 more
We study the optical spectrum of the exciting B[e] star
Shock-cloud interaction in the Vela SNR observed with XMM-Newton
Miceli, M.; Bocchino, F.; Reale, F. +1 more
We analyzed an XMM-Newton EPIC observation of a bright knot, named FilD, in the northern rim of the Vela SNR, where the shock has encountered a cloud. The good combination of sensitivity, spectral, and spatial resolution allowed us to describe the internal structure of the observed ISM clouds and to obtain estimates of their temperature, density, …
On the nature of the X-ray source in GK Persei
Schmitt, J. H. M. M.; Ness, J. -U.; Vrielmann, S.
We report XMM-Newton observations of the intermediate polar (IP) GK Per on the rise to the 2002 outburst and compare them to Chandra observations during quiescence. The asymmetric spin light curve implies an asymmetric shape of a semi-transparent accretion curtain and we propose a model for its shape. A low Fe xvii (λλ15.01/15.26 Å) line flux rati…
On the "injection problem" at the solar wind termination shock
Hilchenbach, M.; Kallenbach, R.; Bamert, K. +2 more
This article presents an integrated analytical model on the injection efficiencies of the different ion species of the Anomalous component of the Cosmic Rays (ACRs) at the solar wind termination shock. We find that the injection into diffusive (first-order Fermi) acceleration is dominated by parallel ion diffusion and not by perpendicular diffusio…
HD 121190: A cool multiperiodic slowly pulsating B star with moderate rotation
Aerts, C.; Kolenberg, K.
We have gathered and analysed multicolour Geneva photometry and high-resolution spectroscopy of the stars HD 121190 (B9V) and HD 106419 (B9III) whose short-term periodic variability had become evident from their HIPPARCOS data. We find three significant frequencies for HD 121190 in the Geneva data: 2.6831, 2.6199 and 2.4713 c d-1 and cl…
X-ray to UV variability correlation in MCG-6-30-15
Papadakis, I.; Arévalo, P.; Kuhlbrodt, B. +1 more
We used a ∼ 300 ks long XMM-Newton observation of the Seyfert 1 galaxy MCG-6-30-15 to study the correlation between the 0.2-10 keV X-ray and the 3000-4000 ÅU bands. We found a significant correlation peak at a time lag of τmax ∼ 160 ks where the UV flux variations preceded the variations in the X-ray band. We interpret this result as ev…
X-ray tomography of a cometary bow shock
Dennerl, K.; Wegmann, R.
The volume intensity of the cometary X-ray emission is enhanced behind the bow shock by a factor of up to three. This effect offers the opportunity to identify the bow shock by a tomographic method in X-ray images of comets. By an analysis of the X-ray data obtained by XMM-Newton from Comet C/2000 WM1 (LINEAR) we obtain information on the position…
A changing inner radius in the accretion disc of Q0056-363?
Maiolino, R.; Bianchi, S.; Falocco, S. +4 more
Q0056-363 is the most powerful X-ray quasar known to exhibit a broad, likely relativistic iron line (Porquet & Reeves 2003, A&A, 408, 119). It has been observed twice by XMM-Newton, three and half years apart (July 2000 and December 2003). In the second observation, the UV and soft X-ray fluxes were fainter, the hard X-ray power law flatte…
V453 Oph: a s-process enriched, but carbon-deficient RV Tauri star of low intrinsic metallicity
van Winckel, H.; Siess, L.; Goriely, S. +2 more
This paper reports the detection of a heavy element enriched RV Tauri variable with an abundance pattern that differs significantly from a standard s-process enriched object: