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dc.contributor.authorRiaz, B.
dc.date.accessioned2013-01-07T12:29:23Z
dc.date.available2013-01-07T12:29:23Z
dc.date.issued2009-08-10
dc.identifier.citationRiaz , B 2009 , ' Silicate evolution in brown dwarf disks ' , The Astrophysical Journal , vol. 701 , no. 1 , pp. 571-586 . https://doi.org/10.1088/0004-637X/701/1/571
dc.identifier.issn0004-637X
dc.identifier.otherPURE: 497209
dc.identifier.otherPURE UUID: 2c9acf13-ae36-4ddd-acc9-ee878c6d3333
dc.identifier.otherWOS: 000268341800049
dc.identifier.otherScopus: 70450124854
dc.identifier.urihttp://hdl.handle.net/2299/9492
dc.description.abstractWe present a compositional analysis of the 10 mu m silicate spectra for brown dwarf disks in the Taurus and Upper Scorpius (UppSco) star-forming regions, using archival Spitzer/Infrared Spectrograph observations. A variety in the silicate features is observed, ranging from a narrow profile with a peak at 9.8 mu m, to nearly flat, low-contrast features. For most objects, we find nearly equal fractions for the large-grain and crystalline mass fractions, indicating both processes to be active in these disks. The median crystalline mass fraction for the Taurus brown dwarfs is found to be 20%, a factor of similar to 2 higher than the median reported for the higher mass stars in Taurus. The large-grain mass fractions are found to increase with an increasing strength in the X-ray emission, while the opposite trend is observed for the crystalline mass fractions. A small 5% of the Taurus brown dwarfs are still found to be dominated by pristine interstellar medium-like dust, with an amorphous submicron grain mass fraction of similar to 87%. For 15% of the objects, we find a negligible large-grain mass fraction, but a >60% small amorphous silicate fraction. These may be the cases where substantial grain growth and dust sedimentation have occurred in the disks, resulting in a high fraction of amorphous submicron grains in the disk surface. Among the UppSco brown dwarfs, only usd161939 has a signal-to-noise ratio high enough to properly model its silicate spectrum. We find a 74% small amorphous grain and a similar to 26% crystalline mass fraction for this object.en
dc.format.extent16
dc.language.isoeng
dc.relation.ispartofThe Astrophysical Journal
dc.subjectcircumstellar matter
dc.subjectopen clusters and associations: individual (Taurus, Upper Scorpius)
dc.subjectstars: abundances
dc.subjectstars: low-mass, brown dwarfs
dc.subjectSCORPIUS OB ASSOCIATION
dc.subjectTAURUS MOLECULAR CLOUD
dc.subjectYOUNG SUBSTELLAR OBJECTS
dc.subjectLOW-MASS STARS
dc.subjectPROTOPLANETARY DISKS
dc.subjectGRAIN-GROWTH
dc.subjectCRYSTALLINE SILICATES
dc.subjectCIRCUMSTELLAR DISKS
dc.subjectDUST GRAINS
dc.subjectMINERALOGY
dc.titleSilicate evolution in brown dwarf disksen
dc.contributor.institutionSchool of Physics, Astronomy and Mathematics
dc.contributor.institutionScience & Technology Research Institute
dc.contributor.institutionCentre for Astrophysics Research
dc.description.statusPeer reviewed
dc.identifier.urlhttp://www.scopus.com/inward/record.url?scp=70450124854&partnerID=8YFLogxK
rioxxterms.versionAM
rioxxterms.versionofrecordhttps://doi.org/10.1088/0004-637X/701/1/571
rioxxterms.typeJournal Article/Review
herts.preservation.rarelyaccessedtrue


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