Search Publications
Lithium abundances for early F stars: new observational constraints for the Li dilution
Recio-Blanco, A.; de Laverny, P.; de Medeiros, J. R. +2 more
Aims.To investigate any correlation between Li abundances and rotational velocities among F-G evolved stars, we study a large sample of early F stars from the Bright Star Catalogue (BSC), most of them classified in the literature as giant stars.
Methods.Physical parameters and Li abundances are estimated for each star, often for the first time,…
On the dynamical stability of the Rosetta orbiter. I.
Mysen, E.; Aksnes, K.
The Rosetta probe is to monitor, from a bound orbit, its primary target comet 67P/Churyumov-Gerasimenko for extended periods of time. As a preliminary assessment of the challenges involved, the strengths of the effects which perturb the spacecraft's cometocentric Keplerian trajectory are evaluated. It is found that in our adopted nominal scenario,…
Restoring color-magnitude diagrams with the Richardson-Lucy algorithm
Cignoni, M.; Shore, S. N.
Aims.We present an application of the Richardson-Lucy algorithm to the analysis of color-magnitude diagrams by converting the CMD into an image and using a restoring point spread function function (psf) derived from the known, often complex, sources of error.
Methods: .We show numerical experiments that demonstrate good recovery of the origina…
PG 0844+349 revisited - is there any outflow?
Wang, T.; Brinkmann, W.; Grupe, D. +1 more
Aims.The detection of high velocity absorption lines from highly ionized material has been reported recently from the X-ray spectrum of the narrow line Seyfert 1 galaxy PG 0844+349 and were interpreted as a relativistic outflow from the source. We studied this outflow because it would have important implications for our understanding of narrow lin…
Time-dependent 3D modulation of Jovian electrons. Comparison with Ulysses/KET observations
Fichtner, H.; Kissmann, R.; Lange, D.
We report on the modelling of the time-dependent transport of a few MeV electrons in the heliosphere. These low-energetic electrons, observed with the Kiel Electron Telescope (KET) on board the Ulysses spacecraft, are for the first time simulated over a complete solar activity cycle on the basis of a time-dependent three-dimensional modulation mod…
Dynamic features in the solar atmosphere with unusual spectral line enhancements and Doppler-shifts
Doyle, J. G.; Dzifćáková, E.; Madjarska, M. S. +2 more
Context.The solar atmosphere contains a wide variety of transient features, here, we discuss data relating to one such feature.
Aims.To explore via simultaneous spectral and imaging data the nature of high-velocity flow events in the solar transition region.
Methods.High spectral and temporal resolution data from SUMER/SoHO plus high resol…
INTEGRAL detection of hard X-rays from NGC 6334: nonthermal emission from colliding winds or an AGN?
McBreen, B.; Terrier, R.; Rauw, G. +12 more
Aims.We report the detection of hard X-ray emission from the field of the star-forming region NGC 6334 with the International Gamma-Ray Astrophysics Laboratory INTEGRAL .Methods.The JEM-X monitor and ISGRI imager aboard INTEGRAL and Chandra ACIS imager were used to construct 3-80 keV images and spectra of NGC 6334.Results.The 3-10 keV and 10-35 ke…
On the Lyman α and β lines in solar coronal streamers
Li, B.; Labrosse, N.; Li, X.
Aims.We investigate the formation of the H I Lyman α and Lyman β lines in an equatorial coronal streamer. Particular attention is paid to frequency redistribution for the scattering of the incident radiation. The properties of the spectral lines are studied.
Methods.The coronal model is given by a global 2.5D three fluid solar wind model with α…
Optimal filtering of solar images using soft morphological processing techniques
Fletcher, L.; Marshall, S.; Hough, K.
Context: .CCD images obtained by space-based astronomy and solar physics are frequently spoiled by galactic and solar cosmic rays, and particles in the Earth's radiation belt, which produces an overlaid, often saturated, speckle.
Aims: .We describe the development and application of a new image-processing technique for the removal of this nois…
EUV line intensity distribution in the solar atmosphere: differences between a polar coronal hole and its equatorial extension
Raju, K. P.; Bromage, B. J. I.
Intensity histograms of 14 EUV emission lines in a polar coronal hole, its equatorial extension, the "Elephant's Trunk", and the adjacent quiet Sun regions have been obtained from SOHO/CDS observations made in August and September 1996. Differences between the quiet region and coronal hole on the one hand, and the polar hole and the equatorial ext…