Search Publications
Transit mapping of a starspot on CoRoT-2. Probing a stellar surface with planetary transits
Schmitt, J. H. M. M.; Czesla, S.; Guenther, E. W. +4 more
We analyze variations in the transit lightcurves of CoRoT-2b, a massive hot Jupiter orbiting a highly active G star. We use one transit lightcurve to eclipse-map a photospheric spot occulted by the planet. In this case study we determine the size and longitude of the eclipsed portion of the starspot and systematically study the corresponding uncer…
Evolution of the early-type galaxy fraction in clusters since z = 0.8
Pelló, R.; White, S. D. M.; Milvang-Jensen, B. +13 more
We study the morphological content of a large sample of high-redshift clusters to determine its dependence on cluster mass and redshift. Quantitative morphologies are based on PSF-convolved, 2D bulge+disk decompositions of cluster and field galaxies on deep Very Large Telescope FORS2 images of eighteen, optically-selected galaxy clusters at 0.45 &…
Model atmospheres of chemically peculiar stars. Self-consistent empirical stratified model of HD 24712
Shulyak, D.; Ryabchikova, T.; Kochukhov, O. +1 more
Context: High-resolution spectra of some chemically peculiar stars clearly demonstrate the presence of strong abundance gradients in their atmospheres. However, these inhomogeneities are usually ignored in the standard scheme of model atmosphere calculations, breaking the consistency between model structure and spectroscopically derived abundance …
Multi-wavelength study of X-ray luminous clusters at z ~ 0.3. I. Star-formation activity of cluster galaxies
Böhringer, H.; Biviano, A.; Pierini, D. +1 more
Context: The current paradigm of cosmic formation and evolution of galaxy clusters foresees growth mostly through merging. Galaxies in the infall region or in the core of a cluster undergo transformations owing to different environmental stresses.
Aims: For two X-ray luminous clusters at redshift z 0.3 with opposite X-ray morphologies (i.e., d…
The circumstellar disc in the Bok globule CB 26. Multi-wavelength observations and modelling of the dust disc and envelope
Pinte, C.; Ménard, F.; Duchêne, G. +10 more
Context: Circumstellar discs are expected to be the nursery of planets. Grain growth within such discs is the first step in the planet formation process. The Bok globule CB 26 harbours such a young disc.
Aims: We present a detailed model of the edge-on circumstellar disc and its envelope in the Bok globule CB 26.
Methods: The model is base…
The solar chromosphere at high resolution with IBIS. III. Comparison of Ca II K and Ca II 854.2 nm imaging
Cauzzi, G.; Uitenbroek, H.; Reardon, K. P.
Aims: Filtergrams obtained in Ca II H, Ca II K, and Hα are often employed as diagnostics of the solar chromosphere. The vastly disparate appearance between the typical filtergrams in these different lines calls into question the nature of what is actually being observed. We investigate the lack of obvious structures of magnetic origin such as fibr…
Rate and nature of false positives in the CoRoT exoplanet search
Mazeh, T.; Aigrain, S.; Zucker, S. +47 more
Context: The CoRoT satellite searches for planets by applying the transit method, monitoring up to 12 000 stars in the galactic plane for 150 days in each observing run. This search is contaminated by a large fraction of false positives, caused by different eclipsing binary configurations that might be confused with a transiting planet.
Aims: …
Benchmarking atomic data for astrophysics: Fe XVII EUV lines
Del Zanna, G.; Ishikawa, Y.
In the light of accurate structure and scattering calculations for Fe XVII, we review the status of identifications in the EUV spectrum of this ion using various experimental data, from the X-rays to the UV. Most previous identifications are confirmed, although a critical revision leads to changes in many wavelength values, in particular for the 2…
Altair - the ``hottest'' magnetically active star in X-rays
Schmitt, J. H. M. M.; Robrade, J.
Context: The onset of stellar magnetic activity is related to the operation of dynamo processes that require the development of an outer convective layer. This transition of stellar interior structure is expected to occur in late A-type stars.
Aims: The A7 star Altair is one of the hottest magnetically active stars. Its proximity to the Sun al…
Ionization processes in the atmosphere of Titan. I. Ionization in the whole atmosphere
Gronoff, G.; Lilensten, J.; Desorgher, L. +1 more
Context: The Cassini probe regularly passes in the vicinity of Titan, revealing new insights into particle precipitation thanks to the electron and proton spectrometer. Moreover, the Huygens probe has revealed an ionized layer at 65~km induced by cosmic rays. The impact of these different particles on the chemistry of Titan is probably very strong…