dc.contributor.author | Riaz, B. | |
dc.date.accessioned | 2013-01-07T12:29:23Z | |
dc.date.available | 2013-01-07T12:29:23Z | |
dc.date.issued | 2009-08-10 | |
dc.identifier.citation | Riaz , 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.issn | 0004-637X | |
dc.identifier.uri | http://hdl.handle.net/2299/9492 | |
dc.description.abstract | We 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.extent | 16 | |
dc.format.extent | 1118610 | |
dc.language.iso | eng | |
dc.relation.ispartof | The Astrophysical Journal | |
dc.subject | circumstellar matter | |
dc.subject | open clusters and associations: individual (Taurus, Upper Scorpius) | |
dc.subject | stars: abundances | |
dc.subject | stars: low-mass, brown dwarfs | |
dc.subject | SCORPIUS OB ASSOCIATION | |
dc.subject | TAURUS MOLECULAR CLOUD | |
dc.subject | YOUNG SUBSTELLAR OBJECTS | |
dc.subject | LOW-MASS STARS | |
dc.subject | PROTOPLANETARY DISKS | |
dc.subject | GRAIN-GROWTH | |
dc.subject | CRYSTALLINE SILICATES | |
dc.subject | CIRCUMSTELLAR DISKS | |
dc.subject | DUST GRAINS | |
dc.subject | MINERALOGY | |
dc.title | Silicate evolution in brown dwarf disks | en |
dc.contributor.institution | School of Physics, Astronomy and Mathematics | |
dc.description.status | Peer reviewed | |
dc.identifier.url | http://www.scopus.com/inward/record.url?scp=70450124854&partnerID=8YFLogxK | |
rioxxterms.versionofrecord | 10.1088/0004-637X/701/1/571 | |
rioxxterms.type | Journal Article/Review | |
herts.preservation.rarelyaccessed | true | |