Search Publications
Extragalactic optical-infrared background radiation, its time evolution and the cosmic photon-photon opacity
Rodighiero, G.; Franceschini, A.; Vaccari, M.
Context: The background radiation in the optical and the infrared cause energy loss in the propagation of high energy particles through space. In particular, TeV observations with Cherenkov telescopes of extragalactic sources are influenced by the opacity effects due to the interaction of the very high-energy source photons with the background lig…
Circumstellar water vapour in M-type AGB stars: radiative transfer models, abundances, and predictions for HIFI
Olofsson, H.; Schöier, F. L.; Bergman, P. +2 more
Context: Surprisingly high amounts of H2O have recently been reported in the circumstellar envelope around the M-type asymptotic giant branch star W Hya. This has lead to the speculation that evaporation of icy cometary or planetary bodies might be an effective ongoing mechanism in such systems. However, substantial uncertainties remain, as the re…
Spatially resolved dusty torus toward the red supergiant WOH G64 in the Large Magellanic Cloud
Weigelt, G.; Hofmann, K. -H.; Driebe, T. +2 more
Aims: We present N-band spectro-interferometric observations of the red supergiant
Dust processing in photodissociation regions. Mid-IR emission modelling
Abergel, A.; Habart, E.; Compiègne, M. +1 more
Context: Mid-infrared spectroscopy of dense illuminated ridges (or photodissociation regions, PDRs) suggests dust evolution. Such evolution must be reflected in the gas physical properties through processes like photo-electric heating or H2 formation.
Aims: With Spitzer Infrared Spectrograph (IRS) and ISOCAM data, we study the mid-IR emission …
Molecular jets driven by high-mass protostars: a detailed study of the IRAS 20126+4104 jet
Eislöffel, J.; Nisini, B.; Giannini, T. +2 more
Context: Protostellar jets from intermediate- and high-mass protostars provide an excellent opportunity to understand the mechanisms responsible for intermediate- and high-mass star-formation. A crucial question is if they are scaled-up versions of their low-mass counterparts. Such high-mass jets are relatively rare and, usually, they are distant …
The characteristics of the IR emission features in the spectra of Herbig Ae stars: evidence for chemical evolution
Waters, L. B. F. M.; Henning, T.; Tielens, A. G. G. M. +4 more
Context: Infrared (IR) spectra provide a prime tool to study the characteristics of polycyclic aromatic hydrocarbon (PAH) molecules in regions of star formation. Herbig Ae/Be stars are a class of young pre-main sequence stellar objects of intermediate mass. They are known to have varying amounts of natal cloud material still present in their direc…
Carriers of the mid-IR emission bands in PNe reanalysed. Evidence of a link between circumstellar and interstellar aromatic dust
Joblin, C.; Szczerba, R.; Berné, O. +1 more
Context: It has been shown that the diversity of the aromatic emission features can be rationalized into different classes of objects, in which differences between circumstellar and interstellar matter are emphasised.
Aims: We probe the links between the mid-IR emitters observed in planetary nebulae (PNe) and their counterparts in the interste…
Extended Red Emission and the evolution of carbonaceous nanograins in NGC 7023
Cuillandre, J. -C.; Joblin, C.; Thomas, J. +3 more
Context: Extended Red Emission (ERE) was recently attributed to the photo-luminescence of either doubly ionized Polycyclic Aromatic Hydrocarbons (PAH++), or charged PAH dimers ([PAH{2}] ^+).
Aims: We analysed the visible and mid-infrared (mid-IR) dust emission in the North-West and South photo-dissociation regions of the reflection …
Abundances in planetary nebulae: NGC 6826
Pottasch, S. R.; Surendiranath, R.
Aims: We determine the chemical abundances and other parameters of the nebula NGC 6826 and its central star.
Methods: We present new ISO spectra and combine them with archival IUE and optical spectra from the literature to get a complete, extinction-corrected, spectrum. The chemical composition of the nebula is then calculated in two ways, fir…
Abundances of planetary nebulae NGC 3242 and NGC 6369
Pottasch, S. R.; Bernard-Salas, J.
The spectra of the planetary nebulae