Accueil > Séminaires d’Astrophysique > Dust in C-rich proto-planetary and planetary nebulae


Dust in C-rich proto-planetary and planetary nebulae

Ryszard Szczerba (Nicolaus Copernicus Astronomical Center, Torun, Pologne)

Par Stephane Charpinet - 21/05/2007


Séminaires d’Astrophysique

de l’Observatoire Midi-Pyrénées

Séminaire de


 (Nicolaus Copernicus Astronomical Center, Torun, Pologne)

Jeudi 7 Juin 2007 à 11h


Dust in C-rich proto-planetary and planetary nebulae

The presence of unidentified infra-red (UIR) bands around 3.3, 6.2, ``7.7’’, 8.6 and 11.3 micrometers (and at longer wavelengths) in many astronomical objects is commonly attributed to polycyclic aromatic hydrocarbon (PAH) molecules which are excited by UV photons. Among objects which show pronounced UIR bands there are proto-planetary and planetary nebulae (PPNe and PNe), objects with relatively well established physical conditions. To investigate the overall evolution of UIR band features with hardening of UV radiation (increase of the star’s effective temperature) we have analysed ISO spectra for 20 galactic proto-planetary nebulae and about 10 planetary nebulae with Wolf-Rayet central stars. In addition, the recent Spitzer observations allow us to analyze UIR bands from PPNe and PNe in LMC, i.e. from objects of different metallicity but located at similar distance. I will present our measurements of UIR bands in evolutionary advanced stars from Milky Way and from LMC and argue that some systematic changes of the UIR features with the star’s effective temperature may be due to an increase of the ionization state of their carriers.



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