Search Publications
Average Fe Kα emission from distant AGN
Ebrero, J.; Page, M. J.; Barcons, X. +7 more
Context: One of the most important parameters in the XRB (X-ray background) synthesis models is the average efficiency of accretion onto SMBH (super-massive black holes). This can be inferred from the shape of broad relativistic Fe lines seen in X-ray spectra of AGN (active galactic nuclei). Several studies have tried to measure the mean Fe emissi…
The Ly-α profile and center-to-limb variation of the quiet Sun
Curdt, W.; Teriaca, L.; Tian, H. +2 more
Aims: We study the emission of the hydrogen Lyman-α line in the quiet Sun, its center-to-limb variation, and its radiance distribution. We also compare quasi-simultaneous Ly-α and Ly-β line profiles.
Methods: We used the high spectral and spatial resolution of the SUMER spectrometer and completed raster scans at various locations along the dis…
The long-period Galactic Cepheid RS Puppis. I. A geometric distance from its light echoes
Szabados, L.; Kervella, P.; Bersier, D. +4 more
Context: The bright southern Cepheid RS Pup is surrounded by a circumstellar nebula reflecting the light from the central star. The propagation of the light variations from the Cepheid inside the dusty nebula creates spectacular light echoes that can be observed up to large distances from the star itself. This phenomenon is currently unique in thi…
Dynamics of coronal mass ejections. The mass-scaling of the aerodynamic drag
Vršnak, B.; Vrbanec, D.; Čalogović, J.
Context: Coronal and interplanetary propagation of coronal mass ejections (CMEs) is strongly affected by aerodynamic drag.
Aims: The dependence of the drag acceleration on the mass of the CMEs is investigated to establish a quantitative empirical relationship, which might be important in semi-empirical space-weather forecasting.
Methods: W…
Solar off-limb line widths: Alfvén waves, ion-cyclotron waves, and preferential heating
Dolla, L.; Solomon, J.
Context: Alfvén waves and ion-cyclotron absorption of high-frequency waves are frequently brought into models devoted to coronal heating and fast solar-wind acceleration. Signatures of ion-cyclotron resonance have already been observed in situ in the solar wind (HELIOS spacecrafts) and, recently, in the upper corona (UVCS/SOHO remote-sensing resul…
XMM-Newton observations of the diffuse X-ray emission in the starburst galaxy NGC 253
Pietsch, W.; Read, A. M.; Freyberg, M. J. +4 more
Aims: We present a study of the diffuse X-ray emission in the halo and the disc of the starburst galaxy NGC 253.
Methods: After removing point-like sources, we analysed XMM-Newton images, hardness ratio maps and spectra from several regions in the halo and the disc. We introduce a method to produce vignetting corrected images from the EPIC pn …
Modelling the Venusian airglow
Leblanc, F.; Gronoff, G.; Lilensten, J. +3 more
Context: Modelling of the Venusian ionosphere fluorescence is required, to analyse data being collected by the SPICAV instrument onboard Venus Express.
Aims: We present the modelling of the production of excited states of O, CO and N2, which enables the computation of nightglow emissions. In the dayside, we compute several emissions, taking ad…
Supergranules over the solar cycle
Meunier, N.; Roudier, T.; Rieutord, M.
Context: The origin of supergranulation has not been understood yet. Contradictory results have been obtained in the past concerning the relation between supergranule properties (mostly cell size) and the solar cycle.
Aims: We propose to study the variation in supergranule cell sizes and velocity fields over the solar cycle, as well as the int…
Simultaneous absolute timing of the Crab pulsar at radio and optical wavelengths
Schulz, R.; Oosterbroek, T.; Golden, A. +7 more
Context: The Crab pulsar emits across a large part of the electromagnetic spectrum. Determining the time delay between the emission at different wavelengths will allow to better constrain the site and mechanism of the emission. We have simultaneously observed the Crab Pulsar in the optical with S-Cam, an instrument based on Superconducting Tunneli…
The directivity of solar type III bursts at hectometer and kilometer wavelengths: Wind-Ulysses observations
Maksimovic, M.; Bonnin, X.; Hoang, S.
We investigate the directivity of solar type III radio bursts at hectometer and kilometer wavelengths using radio data recorded simultaneously by the Wind and Ulysses spacecraft which are widely separated in heliocentric longitude and latitude. From the positions of the associated flares and the solar wind speed and plasma density measured aboard …