The Dust Composition of Transitional Disks
First Author:
Manoj Puravankara
Email: manoj AT pas.rochester.edu
University of Rochester
500 Wilson Blvd, PO Box 270171
Rochester, NY-14627-0171 USA
Coauthors:
Kim, Kyoung Hee, University of Rochester
Sargent, Ben, University of Rochester
Furlan, Elise, JPL, Caltech
McClure, Melissa, University of Michigan
Watson, Dan, University of Rochester
Forrest, William, University of Rochester
Espaillat, Catherine, University of Michigan
Calvet, Nuria, University of MIchigan
Luhman, Kevin, Penn State
Abstract
Dust composition analysis of the Spitzer IRS spectra of some 200 youngstars in the three nearby star forming regions of Taurus, Chamaeleon I, and Ophiuchus indicates that an overwhelming majority of these classII objects have crystalline grains in the protoplanetary disks surrounding them. The crystalline dust mass fraction in these disks ranges from a few percent to more than 90%. 'Transitional disks' - disks with inner holes or gaps - are among the objects which show very low crystalline dust content. The IRS spectra of most transitional disks show pristine silicate profiles, very similar to the interstellar silicate profile. This is surprising, as transitional disks are thought to be more evolved than typical T Tauri disks, for which we find evidence for significant crystallization to have occured. The low crystalline dust content of transitional disks argues for a connection between disk structure and dust crystallization and has important implications for disk evolution.
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