Search Publications
Modulation in the solar irradiance due to surface magnetism during cycles 21, 22 and 23
Jain, K.; Hasan, S. S.
Magnetic field indices derived from synoptic magnetograms of the Mt. Wilson Observatory, i.e. Magnetic Plage Strength Index (MPSI) and Mt. Wilson Sunspot Index (MWSI), are used to study the effects of surface magnetism on total solar irradiance variability during solar cycles 21, 22 and 23. We find that most of the solar cycle variation in the tot…
XMM-Newton spectra of hard spectrum Rosat AGN: X-ray absorption and optical reddening
Page, M. J.; Carrera, F. J.; Mittaz, J. P. D.
We present the XMM-Newton spectra of three low-redshift intermediate Seyferts (one Sy 1.5, and two Sy 1.8), from our survey of hard spectrum Rosat sources. The three AGN are well fitted by absorbed powerlaws, with intrinsic nuclear photoelectric absorption from column densities between 1.3 and 4.0 × 1021 cm-2. In the brightes…
INTEGRAL observation of 3EG J1736-2908
Gehrels, N.; Grandi, P.; Chaty, S. +10 more
The possible identification by INTEGRAL of the EGRET source 3EG J1736-2908 with the active galactic nucleus GRS 1734-292 is discussed. The latter was discovered in 1990 and later identified with a Seyfert 1 galaxy. At the time of the compilation of the 3rd EGRET Catalog, it was not considered as a possible counterpart of the source 3EG J1736-2908,…
An estimate of the D/H ratio in Jupiter and Saturn's regular icy satellites - Implications for the Titan Huygens mission
Mousis, O.
The solar nebula model described by Dubrulle (\cite{Dubrulle1993}) and Drouart et al. (\cite{Drouart1999}) is used to predict the D/H ratio in H2O ice of both Jovian and Saturnian regular satellite systems. These calculations take into account recent scenarios of formation of Jupiter and Saturn's large regular icy satellites developed f…
Conversion of bulk kinetic energy into radiation in AGNs and GRBs: Particle transport effects
Vainio, R.; Schlickeiser, R.; Pohl, M.
We investigate the spatial structure of collisionless collision fronts in relativistic outflows interacting with ambient material. As a result of the interaction, ambient particles are picked up by the outflow and generate transverse plasma waves via streaming instabilities. Pick-up particle transport under the influence of self-generated turbulen…
On the analysis of band 3 of the ISO-SWS calibration sources
Shipman, R. F.; Decin, L.; Kester, D. +4 more
We analyse ISO-SWS 01 (R ∼ 1500) 12-27.5 µm (band 3) spectra of the 10 standard calibration stars with the highest flux using synthetic spectra generated from (MARCS) atmosphere models. The comparison between the observed and synthetic spectra reveals the quality of (1) the atmospheric model construction and subsequent synthetic spectra comp…
η Carinae: The 1998 brightening and the smearing-out effect
Sterken, C.; van Genderen, A. M.
A comparison of broad-band photometry of the Homunculus (ground-based data) and of broad-band and narrow-band photometry of the central region (HST-based) from 1997 to 2003 reveals that, apart from the brightening in 1998, the Homunculus as well as the central star varied in a very similar way. This excludes smearing-out effects as an explanation …
The composite starburst/AGN nature of the superwind galaxy NGC 4666
Palazzi, E.; Cappi, M.; Franceschini, A. +6 more
We report the discovery of a Compton-thick AGN and of intense star-formation activity in the nucleus and disk, respectively, of the nearly edge-on superwind galaxy NGC 4666. Spatially unresolved emission is detected by BeppoSAX only at energies <10 keV, whereas spatially resolved emission from the whole disk is detected by XMM-Newton. A promine…
The discovery of hard X-ray emission in the persistent flux of the Rapid Burster
Frontera, F.; Goldoni, P.; Stella, L. +3 more
We report the first detection with INTEGRAL of persistent hard X-ray emission (20 to 100 keV) from the Rapid Burster (MXB 1730-335), and describe its full spectrum from 3 to 100 keV. The source was detected on February/March 2003 during one of its recurrent outbursts. The source was clearly detected with a high signal to noise ratio during the sin…
Physical parameters of helium-rich subdwarf B stars from spectral energy distributions
Jeffery, C. S.; Ahmad, A.
We present effective temperatures and angular radii for eleven helium-rich subdwarf B stars. These are measured using spectral energy distributions from archival IUE spectra and existing optical and infrared photometry. The data have been analysed using a grid of high-gravity helium-rich LTE model atmospheres and a χ2-minimization proce…