[-] Show simple item record

dc.contributor.authorDePew, Kyle Davideng
dc.contributor.authorSpeck, Angela K.eng
dc.contributor.authorDijkstra, Catharinuseng
dc.date.issued2006eng
dc.descriptionhttp://iopscience.iop.org/0004-637X/640/2/971/pdf/0004-637X_640_2_971.pdfeng
dc.description.abstractAsymptotic giant branch (AGB) stars have several interesting infrared spectral features. Approximately half the oxygen-rich AGB stars to be investigated spectroscopically exhibit a feature at ~13 μm. The carrier of this feature has not yet been unequivocally identified but has been attributed to various dust species, including corundum (α-Al2O 3), spinel (MgAl2O4), and silica (SiO 2). In order to constrain the carrier of the 13 μm feature, we have used the one-dimensional radiative transfer code DUSTY to model the effects of composition and optical depth on the shape and strength of the emerging 13 μm feature from corundum and spinel grains. We have modeled various corundum, spinel, corundum-silicate, and spinel-silicate mixtures in dust shells surrounding O-rich AGB stars. These models demonstrate that (1) if corundum is present in these circumstellar dust shells, even at very low relative abundances, a ~13 μm feature should be observed; (2) corundum's weak ~21 μm feature will not be observed, even if it is responsible for the ~13 μm feature; (3) even at low relative abundances, spinel exhibits a feature at 16.8 μm that is not found in observations; and (4) the grains must be spherical. Other grain shapes (spheroids, ellipsoids, and hollow spheres) shift the features to longer wavelengths for both spinel and corundum. Our models show that spinel is unlikely to be the carrier of the 13 μm feature. The case for corundum as the carrier is strengthened but not yet proven.eng
dc.description.sponsorshipThis work is supported in part by NASA grant APRA04-0000-0041.eng
dc.identifier.citationKyle DePew et al. 2006 ApJ 640 971eng
dc.identifier.issn0004-637Xeng
dc.identifier.urihttp://hdl.handle.net/10355/9925eng
dc.languageEnglisheng
dc.publisherAmerican Astronomical Societyeng
dc.relation.ispartofcollectionUniversity of Missouri--Columbia. College of Arts and Sciences. Department of Physics and Astronomy. Physics and Astronomy publicationseng
dc.subjectinfrared starseng
dc.subject.lcshCircumstellar mattereng
dc.subject.lcshAsymptotic giant branch starseng
dc.titleAstromineralogy of the 13 μm Feature in the Spectra of Oxygen-rich Asymptotic Giant Branch Stars. I. Corundum and Spineleng
dc.typeArticleeng


Files in this item

[PDF]

This item appears in the following Collection(s)

[-] Show simple item record