AAS 204th Meeting, June 2004
Session 41 Spitzer Space Telescope
Topical Related Poster, Tuesday, June 1, 2004, 10:00am-7:00pm, Ballroom

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[41.13] Mid-infrared spectra of Class I protostars in Taurus

J.D. Green, D.M. Watson (University of Rochester), E. Furlan (Cornell University), W.J. Forrest (University of Rochester), C.H. Chen (Jet Propulsion Laboratory), F. Kemper (UCLA), N. Calvet, L. Hartmann (Harvard-Smithsonian Center for Astrophysics), K.I. Uchida (Cornell University), L.D. Keller (Ithaca College), B. Sargent (University of Rochester), G.C. Sloan, T.L. Herter (Cornell University), B.R. Brandl (Sterrewacht Leiden), J.R. Houck, D.J. Barry, P. Hall (Cornell University), P.W. Morris (Spitzer Science Center, Caltech), M. Jura (UCLA), J. Najita (NOAO), P. D'Alessio (Centro de Radioastronomia y Astrofisica, UNAM), P.C. Myers (Harvard-Smithsonian Center for Astrophysics)

We present Spitzer Infrared Spectrograph (IRS)* observations in the 5.3-20 \mum range of five young stellar objects in Taurus that have Class I continuum spectral energy distributions, often taken to represent the younger stellar objects in this star-formation region. The spectra include a rich collection of broad absorption features that we identify with amorphous silicates and various ices, notably those of water, methanol, and carbon dioxide. This is apparently the first detection of such ice features in the disks of low-mass (below a solar mass) young stellar objects. We use these spectral features to estimate the relative contributions of disk and envelope to the absorption spectrum, and compare the spectra to detailed models to derive a view of the thermal structure of these components of circumstellar material. We conclude that the objects represent a range of envelope mass and line-of-sight orientation, and that objects can be classified in terms of these properties from mid-infrared spectra, even in the absence of supporting information from infrared images.

This work is based on observations made with the Spitzer Space Telescope, which is operated by the Jet Propulsion Laboratory, California Institute of Technology under NASA contract 1407. Support for this work was provided by NASA through Contract Number 1257184 issued by JPL/Caltech, and through the Spitzer Fellowship Program, under award 011 808-001.

* The IRS was a collaborative venture between Cornell University and Ball Aerospace Corporation funded by NASA through the Jet Propulsion Laboratory and the Ames Research Center.

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