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E. Polomski (University of Minnesota), D. K. Lynch, R. W. Russell (Aerospace Corporation), M. L. Sitko (University of Cincinnati)
FU Ori objects are among the youngest of the pre-main sequence stars and exhibit many phenomena attributed to active accretion from a circumstellar disk. Doubled absorption lines, line broadening that decreases to long wavelengths, large optical outbursts, and the presence of bipolar outflows have all been linked to disk activity. FU Ori systems also show large extinctions due to circumstellar dust, and are often very faint optically. Infrared and submillimeter observations show strong emission from thermally heated dust grains, and dust masses which are much larger than those for typical T Tauri systems. We have initiated a 3-13 \mum spectroscopic survey of these objects using the Aerospace Corporation Broadband Array Spectrograph System at the NASA IRTF telescope. We present here the initial results from our survey. FU Ori systems show a wide range of spectral features from dust emission, including mid-IR hydrocarbon emission, ice absorption, and silicate emission and absorption. The diversity of the spectra might be attributed to the influence of close companions and disk inclination angles. Fits to these spectra require a series of dust temperatures, suggesting that the emission arises in distinct structures. We discuss the spectral features of these sources, association with disk activity, and the significance of these phenomena for the FU Ori phase of evolution.
This research was supported in part by NASA through the American Astronomical Society's Small Research Grant Program. This work also supported at The Aerospace Corporation by the Internal Research and Development program.
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Bulletin of the American Astronomical Society, 35#5
© 2003. The American Astronomical Soceity.