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Issue A&A
Volume 483, Number 1, May III 2008
Page(s) L9 - L12
Section Letters
DOI http://dx.doi.org/10.1051/0004-6361:200809697
Published online 01 April 2008



A&A 483, L9-L12 (2008)
DOI: 10.1051/0004-6361:200809697

Letter

Is the silicate emission feature only influenced by grain size?

N. V. Voshchinnikov1, 2 and T. Henning3

1  Sobolev Astronomical Institute, St. Petersburg University, Universitetskii prosp. 28, St. Petersburg 198504, Russia
    e-mail: nvv@astro.spbu.ru
2  Isaac Newton Institute of Chile, St. Petersburg Branch, Russia
3  Max-Planck-Institut für Astronomie, Königstuhl 17, 69117 Heidelberg, Germany

(Received 3 March 2008 / Accepted 21 March 2008 )

Abstract
The flattening of the 10  $\mu{\rm m}$ 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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