Volume 483, Number 1, May III 2008
|Page(s)||L9 - L12|
|Published online||01 April 2008|
Letter to the Editor
Is the silicate emission feature only influenced by grain size?*
Sobolev Astronomical Institute, St. Petersburg University, Universitetskii prosp. 28, St. Petersburg 198504, Russia e-mail: firstname.lastname@example.org
2 Isaac Newton Institute of Chile, St. Petersburg Branch, Russia
3 Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany
Accepted: 21 March 2008
The flattening of the 10 silicate emission feature observed in the spectra of T Tauri and Herbig Ae/Be stars is usually interpreted as an indicator of grain growth. We show in this paper that a similar behaviour of the feature shape occurs when the porosity of composite grains varies. We modelled the fluffy aggregates with inclusions of different sizes with multi-layered spheres consisting of amorphous carbon, amorphous silicate, and vacuum. We also found that the inclusion of crystalline silicates in composite porous particles can lead to a shift of the known resonances and production of new ones.
Key words: line: profiles / stars: pre-main-sequence / stars: planetary systems: protoplanetary disks / stars: circumstellar matter / infrared: stars / ISM: dust, extinction
© ESO, 2008
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