Search Publications
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…
Metal abundances in the cool cores of galaxy clusters
Molendi, S.; de Grandi, S.
We use XMM-Newton data to carry out a detailed study of the Si, Fe and Ni abundances in the cool cores of a representative sample of 26 local clusters. We performed a careful evaluation of the systematic uncertainties related to the instruments, the plasma codes and the spectral modeling, finding that the major source of uncertainty is the plasma …
Statistical equilibrium of silicon in the atmospheres of metal-poor stars
Zhao, G.; Mashonkina, L.; Shi, J. R. +1 more
Aims: The statistical equilibrium of neutral and ionized silicon in the atmospheres of metal-poor stars is discussed. Non-local thermodynamic equilibrium effects (NLTE) are investigated and the silicon abundances in metal-poor stars determined.
Methods: We have used high resolution, high signal to noise ratio spectra from the UVES spectragraph…
Partially-erupting prominences: a comparison between observations and model-predicted observables
Mason, H. E.; Fletcher, L.; Qiu, J. +4 more
Aims: We investigate several partially-erupting prominences to study their relationship with other CME-associated phenomena and compare these observations with observables predicted by a model of partially-expelled-flux-ropes (Gibson & Fan 2006a, ApJ, 637, L65; 2006b, J. Geophys. Res., 111, 12103).
Methods: We studied 6 selected events wit…
Hunting high and low: XMM monitoring of the eclipsing polar HU Aquarii
Dhillon, V. S.; Marsh, T. R.; Littlefair, S. P. +5 more
Aims: We want to study the temporal and spectral behaviour of HU Aqr in the X-ray domain during different accretion states.
Methods: We obtained spectra and light curves from four different XMM-Newton pointings covering intermediate and low states. The X-ray observations were accompanied with high time resolution photometry obtained with the O…