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          Institute: MPI für Astronomie     Collection: Publikationen_mpia     Display Documents



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ID: 559268.0, MPI für Astronomie / Publikationen_mpia
Dust evolution in protoplanetary disks around Herbig Ae/Be Stars—the Spitzer View
Authors:Juhász, A.; Bouwman, J.; Henning, Th; Acke, B.; van den Ancker, M. E.; Meeus, G.; Dominik, C.; Min, M.; Tielens, A. G. G. M.; Waters, L. B. F. M.
Language:English
Date of Publication (YYYY-MM-DD):2010
Title of Journal:The Astrophysical Journal
Journal Abbrev.:ApJ
Volume:721
Issue / Number:1
Start Page:431
End Page:455
Review Status:Peer-review
Audience:Experts Only
Abstract / Description:In this paper, we present mid-infrared spectra of a comprehensive set of Herbig Ae/Be stars observed with the Spitzer Space Telescope. The signal-to-noise ratio of these spectra is very high, ranging between about a hundred and several hundreds. During the analysis of these data we tested the validity of standardized protoplanetary dust models and studied grain growth and crystal formation. On the basis of the analyzed spectra, the major constituents of protoplanetary dust around Herbig Ae/Be stars are amorphous silicates with olivine and pyroxene stoichiometry, crystalline forsterite, and enstatite and silica. No other solid-state features, indicating other abundant dust species, are present in the Spitzer spectra. Deviations of the synthetic spectra from the observations are most likely related to grain shape effects and uncertainties in the iron content of the dust grains. Our analysis revealed that larger grains are more abundant in the disk atmosphere of flatter disks than in that of flared disks, indicating that grain growth and sedimentation decrease the disk flaring. We did not find, however, correlations between the value of crystallinity and any of the investigated system parameters. Our analysis shows that enstatite is more concentrated toward the warm inner disk than forsterite, in contrast to predictions of equilibrium condensation models. None of the three crystal formation mechanisms proposed so far can alone explain all our findings. It is very likely that all three play at least some role in the formation of crystalline silicates.
Free Keywords:circumstellar matter; infrared: planetary systems; infrared: stars; stars: formation; stars: pre-main sequence
External Publication Status:published
Document Type:Article
Communicated by:N. N.
Affiliations:MPI für Astronomie
Identifiers:URL:http://adsabs.harvard.edu/abs/2010ApJ...721..431J [ID No:1]
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