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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. Henning31 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
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